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Topic: Butterfly Labs - Bitforce Single and Mini Rig Box - page 20. (Read 186944 times)

hero member
Activity: 714
Merit: 504
^SEM img of Si wafer edge, scanned 2012-3-12.
Not only that, but BFL is the only one using a chip that has metal packaging, all the rest are plastic, so comparisons between them don't make a whole lot of sense..
metal packaging is a better conductor than plastic. not following there.
All I'm saying is that you shouldn't compare them. All "the other FPGA manufacturers" are using plastic chips.
I was wondering about that. Isn't the BFL single a plastic chip with a metal plate on top? Because if so, then why use the metal plate at all? Wouldn't it be better to put the heatsink directly on the chips? (Just wondering here, not taking sides)
rjk
sr. member
Activity: 448
Merit: 250
1ngldh
If you've done any recent research, most of the "mirror finish" stuff has been debunked, seriously.
link? every chip/heatsink i've ever owned has benefited from lapping. is a "mirror finish" necessary? no. Is it better to have an 800 grit finish than a 120? yes. (not saying it's a 120 grit finish before you micro-analyse. i don't have the chip on hand so i can't tell you what the finish is)
Quite so. I was referring specifically only to the mirror finish, not lapping.

Umm.. they get plenty of "throttling", if they turn the speed up to insane levels. Technically it is just increased error rates, which indicates a need to reduce the speed to compensate.
what constitutes insane levels? I don't know of any other companies using that chip, so i can't say how aggressive their clocks are. I also mentioned its quite possible BFL has a highly optimized bitstream that's putting a lot of thermal pressure on the chip. What i'm saying is their thermal dissipation design is not adequate/optimized and it's causing issues.
thermal paste is designed to increase the surface area contact of chip/heatsink. you want to use the smallest amount possible because metal to metal is a better conductor than metal to tim to metal. logically, if nothing else, the smoother/flatter the surface, the less tim required, the better the cooling.
Flatter, yes, but smoother is debatable because if it is too smooth, the thermal paste might not be able to fill the remaining imperfections, since they are smaller than the paste particle size.

Perhaps you should have a go at the polishing experiment (or whatever else you can think up), and let us know how it works? I am always interested to know the results of real world tests. Before calling it a "mistake", prove that it is wrong.
a single-specific experiment? sure, send me one and i'll have a go at it  Tongue as far as experiments with lapping vs non lapped. google "does lapping increase performance" the general consensus is yes, if the chip isn't flat/has a rough surface, or the heatsink isn't flat/rough surface.
The consensus that I found was that polishing wasn't nearly as important as having a perfectly flat surface.

Not only that, but BFL is the only one using a chip that has metal packaging, all the rest are plastic, so comparisons between them don't make a whole lot of sense..
metal packaging is a better conductor than plastic. not following there.
All I'm saying is that you shouldn't compare them. All "the other FPGA manufacturers" are using plastic chips.
hero member
Activity: 648
Merit: 500
Had you taken the time to run through the grits after sanding the chip, it is quite possible, neigh probable, the singles would not be having such bad throttling issues.
If you've done any recent research, most of the "mirror finish" stuff has been debunked, seriously.
link? every chip/heatsink i've ever owned has benefited from lapping. is a "mirror finish" necessary? no. Is it better to have an 800 grit finish than a 120? yes. (not saying it's a 120 grit finish before you micro-analyse. i don't have the chip on hand so i can't tell you what the finish is)
Other fpga manufacturers are not having throttling issues. Whether that is because they aren't utilizing the chips as well as you are, or because your thermal designs are terrible, is debatable. What isn't debatable is years of research in which techniques provide the best cooling for a chip, regardless of whether it's a cpu, gpu, fpga, or asic.
Umm.. they get plenty of "throttling", if they turn the speed up to insane levels. Technically it is just increased error rates, which indicates a need to reduce the speed to compensate.
what constitutes insane levels? I don't know of any other companies using that chip, so i can't say how aggressive their clocks are. I also mentioned its quite possible BFL has a highly optimized bitstream that's putting a lot of thermal pressure on the chip. What i'm saying is their thermal dissipation design is not adequate/optimized and it's causing issues.
thermal paste is designed to increase the surface area contact of chip/heatsink. you want to use the smallest amount possible because metal to metal is a better conductor than metal to tim to metal. logically, if nothing else, the smoother/flatter the surface, the less tim required, the better the cooling.

As i stated before, I do like your company and i do appreciate what you're trying to do. What I don't like is the excuses you are giving regarding blatant design flaws. It will be interesting to see what the final mini-rig product looks like and whether or not you've learned from mistakes you've made with the singles.
Perhaps you should have a go at the polishing experiment (or whatever else you can think up), and let us know how it works? I am always interested to know the results of real world tests. Before calling it a "mistake", prove that it is wrong.

a single-specific experiment? sure, send me one and i'll have a go at it  Tongue as far as experiments with lapping vs non lapped. google "does lapping increase performance" the general consensus is yes, if the chip isn't flat/has a rough surface, or the heatsink isn't flat/rough surface.


I'm not weighing in on the polished vs unpolished debate (or sanded properly or not) ... but I do want to point out this:

Quote
Other fpga manufacturers are not having throttling issues.

There are no other FPGA manufacturers that are utilizing these chips in this manner, so it's basically a first adopter problem for BFL in design and operation.  Virtually all other FPGA applications do not utilize the chip to the capacity bitcoin mining does, which is, as I understand it, the fundamental problem BFL had in the beginning with their designs and simulations and the start/root cause of all the mystery to begin with.


again, i'm not debating that. If BFL's designers are so good (which again, it seems that they are) that they're running into thermal issues, they should create a solution that actually solves the issue. The box design is not optimized for airflow, the heatsink is not optimized for dissipation, and the sanding was not optimized for heatsink contact, thus creating issues.



EDIT:
I'm not weighing in on the polished vs unpolished debate (or sanded properly or not) ... but I do want to point out this:

Quote
Other fpga manufacturers are not having throttling issues.

There are no other FPGA manufacturers that are utilizing these chips in this manner, so it's basically a first adopter problem for BFL in design and operation.  Virtually all other FPGA applications do not utilize the chip to the capacity bitcoin mining does, which is, as I understand it, the fundamental problem BFL had in the beginning with their designs and simulations and the start/root cause of all the mystery to begin with.

Not only that, but BFL is the only one using a chip that has metal packaging, all the rest are plastic, so comparisons between them don't make a whole lot of sense..

metal packaging is a better conductor than plastic. not following there.
rjk
sr. member
Activity: 448
Merit: 250
1ngldh
I'm not weighing in on the polished vs unpolished debate (or sanded properly or not) ... but I do want to point out this:

Quote
Other fpga manufacturers are not having throttling issues.

There are no other FPGA manufacturers that are utilizing these chips in this manner, so it's basically a first adopter problem for BFL in design and operation.  Virtually all other FPGA applications do not utilize the chip to the capacity bitcoin mining does, which is, as I understand it, the fundamental problem BFL had in the beginning with their designs and simulations and the start/root cause of all the mystery to begin with.

Not only that, but BFL is the only one using a chip that has metal packaging, all the rest are plastic, so comparisons between them don't make a whole lot of sense..
legendary
Activity: 1260
Merit: 1000
I'm not weighing in on the polished vs unpolished debate (or sanded properly or not) ... but I do want to point out this:

Quote
Other fpga manufacturers are not having throttling issues.

There are no other FPGA manufacturers that are utilizing these chips in this manner, so it's basically a first adopter problem for BFL in design and operation.  Virtually all other FPGA applications do not utilize the chip to the capacity bitcoin mining does, which is, as I understand it, the fundamental problem BFL had in the beginning with their designs and simulations and the start/root cause of all the mystery to begin with.
rjk
sr. member
Activity: 448
Merit: 250
1ngldh
Had you taken the time to run through the grits after sanding the chip, it is quite possible, neigh probable, the singles would not be having such bad throttling issues.
If you've done any recent research, most of the "mirror finish" stuff has been debunked, seriously.

Other fpga manufacturers are not having throttling issues. Whether that is because they aren't utilizing the chips as well as you are, or because your thermal designs are terrible, is debatable. What isn't debatable is years of research in which techniques provide the best cooling for a chip, regardless of whether it's a cpu, gpu, fpga, or asic.
Umm.. they get plenty of "throttling", if they turn the speed up to insane levels. Technically it is just increased error rates, which indicates a need to reduce the speed to compensate.

As i stated before, I do like your company and i do appreciate what you're trying to do. What I don't like is the excuses you are giving regarding blatant design flaws. It will be interesting to see what the final mini-rig product looks like and whether or not you've learned from mistakes you've made with the singles.
Perhaps you should have a go at the polishing experiment (or whatever else you can think up), and let us know how it works? I am always interested to know the results of real world tests. Before calling it a "mistake", prove that it is wrong.
hero member
Activity: 648
Merit: 500
Has anyone else noticed how the heatpipe cooler on the rev3 doesn't really cover the second FPGA? It is short by about 5cm. The center of the chip is covered but one whole side is left open.

I noticed this also. If this heatpipe is really custom made the job wasn't done good.

I'm thinking about putting a metal plate between the FPGA's and the heatpipe. This metal plate should cover the full area of both FPGA's and transfer it to the heatpipe. Maybe this could improve the cooling which is obviously mainly limited by the only parted covered FPGA.

Has someone already done this?


Adding any additional substance will only increase thermal resistance and makes cooling less efficient.
The aluminium plate which the heatsink sits on, is a by itself a heat-spreader directly attached to the die inside.


Regards,
BF Labs Inc.

I would agree here, don't add anything extra or your temps will just go up.

The heatsink itself could be better for sure, the aluminum part could be solid copper for start; and I noticed it is slightly short as well, however the copper pipes seem to touch the surface of the chip where the aluminum part cuts off, so that's something I suppose.

Again...  to clarify...   (trying to save unnecessary efforts among users), the chip itself is smaller than the aluminum heat spreader you see.  There is no purpose in trying to extend the heatsink out to the edge of the heat spreader because there is no heat being generated under the edge...  There is only air there.  See picture above for visual reference.

From a technical perspective, I beg to disagree.

There's a thermal resistance RT1 from the die to the heat spreader, and a thermal resistance RT2 from the heat spreader to the cooler. While RT1 cannot be changed, it is a good thing to minimize RT2. One way of minimizing RT2 is by removing the heat from the whole area of the heat spreader.

If you could choose full or partial coverage of the overhang...  certainly full would be an easy choice.  I'm just pointing out that the practical value of doing so in this case is nil.   This is the result of our thermal simulations in designing the heatsink.  The reason the few mm on the edge of the spreader are left uncovered is for package fitting.  

I understand the reasoning behind fitting the heatsink inside the case, but I must disagree with it not having a significant value. Mining is all about min/maxing. the heatsink could have quite easily extended the .25 inch (i'm guessing based on this picture) to gain the extra dissipation. The design of the enclosure for the single is absolutely terrible for dissipating heat, causing the fan to work harder to get less airflow. As far as the hack job you have done sanding the chip, here's an article from 1999 explaining what should be common sense.

 I like the singles, and I like what i've seen of the rig box, you guys have done a decent job at creating a product that fills a need in the market cheaply. That being said, your thermal solutions have been quite terrible/sloppy , and all the designs for the rig box are showing signs of the same backwards logic. I understand every startup company has growing pains, and i don't expect you to get everything right the first time, but please stop making excuses for poor designs and start fixing them.

I think it's important to point out once again that there is *NO* chip under the edge of the heat spreader.  The heat transfer capability from actual chip to heat sink via that area of heat spreader overhang is fantastically insignificant.  IE - it makes no practical difference to the thermal efficiency of the heatsink.  Suggesting otherwise, or promoting the idea that this is a cause of throttling isn't helpful to any user of the product.  I'm not pointing this out to win an argument.  I'm trying to save customers from confusion, misunderstanding and waste of effort.  Each of the chips have their own throttling point.  If you are working to improve the efficiency of any given unit, focusing on this area is akin to a snipe hunt or worse...  it could create heat problems such as the suggested metal plate insertion to try and extend coverage to this area. 

With regards to the 'sanding', extreme care was taken on the run of chips which had that treatment.  It was done with plastic abrasion and full vacuum draw.  90% of the chips shipped have no 'sanding' at all and are free of any marking.

I am not suggesting people should add another heatsink layer to cover the exposed edge of the plate. I am suggesting it would have been easy in the design of the heatsink to extend it to cover the entire surface area, and disagreeing with the reasoning behind not doing it of "it doesn't matter, the loss is minimal". The entire thought process behind a heat SPREADER is to make it easier to dissipate the heat by SPREADING it over a larger area. not covering the added area of the heat SPREADER effectively negates the purpose of putting one on in the first place.

As far as sanding goes, you are mixing up two posts. in regards to how it was done, I was cautioning end users to avoid getting metal dust all over the PCB to avoid shorts. I did not suggest you had not taken the necessary precautions. what I DID say is your sand job is horrible.

DOES NOT EQUAL .

Had you taken the time to run through the grits after sanding the chip, it is quite possible, neigh probable, the singles would not be having such bad throttling issues.

Other fpga manufacturers are not having throttling issues. Whether that is because they aren't utilizing the chips as well as you are, or because your thermal designs are terrible, is debatable. What isn't debatable is years of research in which techniques provide the best cooling for a chip, regardless of whether it's a cpu, gpu, fpga, or asic.

As i stated before, I do like your company and i do appreciate what you're trying to do. What I don't like is the excuses you are giving regarding blatant design flaws. It will be interesting to see what the final mini-rig product looks like and whether or not you've learned from mistakes you've made with the singles.
legendary
Activity: 1666
Merit: 1000
has anyone upgraded to the 872 firmware? If so, how has the performance been?

It worked on one of the 6 singles I received.  I haven't tried it on all 6 but know that 2 won't work (they throttle at 816 firmware).

816 yields a longer term avg of 798 - shows 811 most of the time.

872, as I recall, averages nearer 854 and shows 864 most of the time.
legendary
Activity: 1400
Merit: 1005
So chips are not sanded, it's the heat spreader what we see when someone removes the heatsink...

spiccioli.
The heatspreader is an integral part of the chip packaging, they don't apply it themselves.
... and they should hopefully stop sanding them since we all now know that the chip is an EP3SL150
(just not sure if they are new or 2nd hand)

Correct me if this isn't really a big deal, but aren't rough chip surfaces really bad for heat transfer?

I saw some articles about ppl buffing their GPU heatsinks to a shine prior to installing them.
Yes, but more important is that the surfaces are even.  In other words, you should be able to take a razorblade and put it across the chip in any direction, and not see any gaps where light can shine through.

I'm not sure that it would be feasible to lap the chips as they sit on the board though... so much could get in the way on all the edges, and you don't want to accidentally discharge static electricity to the board while you're rubbing it with sandpaper!  In other words, I wouldn't advise anyone to do it.  But, I would love to see someone try and see what the results are!

i would be more concerned with the metal dust you'd be blanketing the board in.
Yeah, that's a fair point as well.  Would definitely need to blow it off real good with a strong can of air or an air compressor.

has anyone upgraded to the 872 firmware? If so, how has the performance been?
Yes - 855 MH/s using the BitMinter miner.
BFL
full member
Activity: 217
Merit: 100
Has anyone else noticed how the heatpipe cooler on the rev3 doesn't really cover the second FPGA? It is short by about 5cm. The center of the chip is covered but one whole side is left open.

I noticed this also. If this heatpipe is really custom made the job wasn't done good.

I'm thinking about putting a metal plate between the FPGA's and the heatpipe. This metal plate should cover the full area of both FPGA's and transfer it to the heatpipe. Maybe this could improve the cooling which is obviously mainly limited by the only parted covered FPGA.

Has someone already done this?


Adding any additional substance will only increase thermal resistance and makes cooling less efficient.
The aluminium plate which the heatsink sits on, is a by itself a heat-spreader directly attached to the die inside.


Regards,
BF Labs Inc.

I would agree here, don't add anything extra or your temps will just go up.

The heatsink itself could be better for sure, the aluminum part could be solid copper for start; and I noticed it is slightly short as well, however the copper pipes seem to touch the surface of the chip where the aluminum part cuts off, so that's something I suppose.

Again...  to clarify...   (trying to save unnecessary efforts among users), the chip itself is smaller than the aluminum heat spreader you see.  There is no purpose in trying to extend the heatsink out to the edge of the heat spreader because there is no heat being generated under the edge...  There is only air there.  See picture above for visual reference.

From a technical perspective, I beg to disagree.

There's a thermal resistance RT1 from the die to the heat spreader, and a thermal resistance RT2 from the heat spreader to the cooler. While RT1 cannot be changed, it is a good thing to minimize RT2. One way of minimizing RT2 is by removing the heat from the whole area of the heat spreader.

If you could choose full or partial coverage of the overhang...  certainly full would be an easy choice.  I'm just pointing out that the practical value of doing so in this case is nil.   This is the result of our thermal simulations in designing the heatsink.  The reason the few mm on the edge of the spreader are left uncovered is for package fitting.  

I understand the reasoning behind fitting the heatsink inside the case, but I must disagree with it not having a significant value. Mining is all about min/maxing. the heatsink could have quite easily extended the .25 inch (i'm guessing based on this picture) to gain the extra dissipation. The design of the enclosure for the single is absolutely terrible for dissipating heat, causing the fan to work harder to get less airflow. As far as the hack job you have done sanding the chip, here's an article from 1999 explaining what should be common sense.

 I like the singles, and I like what i've seen of the rig box, you guys have done a decent job at creating a product that fills a need in the market cheaply. That being said, your thermal solutions have been quite terrible/sloppy , and all the designs for the rig box are showing signs of the same backwards logic. I understand every startup company has growing pains, and i don't expect you to get everything right the first time, but please stop making excuses for poor designs and start fixing them.

I think it's important to point out once again that there is *NO* chip under the edge of the heat spreader.  The heat transfer capability from actual chip to heat sink via that area of heat spreader overhang is fantastically insignificant.  IE - it makes no practical difference to the thermal efficiency of the heatsink.  Suggesting otherwise, or promoting the idea that this is a cause of throttling isn't helpful to any user of the product.  I'm not pointing this out to win an argument.  I'm trying to save customers from confusion, misunderstanding and waste of effort.  Each of the chips have their own throttling point.  If you are working to improve the efficiency of any given unit, focusing on this area is akin to a snipe hunt or worse...  it could create heat problems such as the suggested metal plate insertion to try and extend coverage to this area. 

With regards to the 'sanding', extreme care was taken on the run of chips which had that treatment.  It was done with plastic abrasion and full vacuum draw.  90% of the chips shipped have no 'sanding' at all and are free of any marking.
full member
Activity: 217
Merit: 100
has anyone upgraded to the 872 firmware? If so, how has the performance been?
hero member
Activity: 648
Merit: 500
So chips are not sanded, it's the heat spreader what we see when someone removes the heatsink...

spiccioli.
The heatspreader is an integral part of the chip packaging, they don't apply it themselves.
... and they should hopefully stop sanding them since we all now know that the chip is an EP3SL150
(just not sure if they are new or 2nd hand)

Correct me if this isn't really a big deal, but aren't rough chip surfaces really bad for heat transfer?

I saw some articles about ppl buffing their GPU heatsinks to a shine prior to installing them.
Yes, but more important is that the surfaces are even.  In other words, you should be able to take a razorblade and put it across the chip in any direction, and not see any gaps where light can shine through.

I'm not sure that it would be feasible to lap the chips as they sit on the board though... so much could get in the way on all the edges, and you don't want to accidentally discharge static electricity to the board while you're rubbing it with sandpaper!  In other words, I wouldn't advise anyone to do it.  But, I would love to see someone try and see what the results are!

i would be more concerned with the metal dust you'd be blanketing the board in.
hero member
Activity: 648
Merit: 500
Has anyone else noticed how the heatpipe cooler on the rev3 doesn't really cover the second FPGA? It is short by about 5cm. The center of the chip is covered but one whole side is left open.

I noticed this also. If this heatpipe is really custom made the job wasn't done good.

I'm thinking about putting a metal plate between the FPGA's and the heatpipe. This metal plate should cover the full area of both FPGA's and transfer it to the heatpipe. Maybe this could improve the cooling which is obviously mainly limited by the only parted covered FPGA.

Has someone already done this?


Adding any additional substance will only increase thermal resistance and makes cooling less efficient.
The aluminium plate which the heatsink sits on, is a by itself a heat-spreader directly attached to the die inside.


Regards,
BF Labs Inc.

I would agree here, don't add anything extra or your temps will just go up.

The heatsink itself could be better for sure, the aluminum part could be solid copper for start; and I noticed it is slightly short as well, however the copper pipes seem to touch the surface of the chip where the aluminum part cuts off, so that's something I suppose.

Again...  to clarify...   (trying to save unnecessary efforts among users), the chip itself is smaller than the aluminum heat spreader you see.  There is no purpose in trying to extend the heatsink out to the edge of the heat spreader because there is no heat being generated under the edge...  There is only air there.  See picture above for visual reference.

From a technical perspective, I beg to disagree.

There's a thermal resistance RT1 from the die to the heat spreader, and a thermal resistance RT2 from the heat spreader to the cooler. While RT1 cannot be changed, it is a good thing to minimize RT2. One way of minimizing RT2 is by removing the heat from the whole area of the heat spreader.

If you could choose full or partial coverage of the overhang...  certainly full would be an easy choice.  I'm just pointing out that the practical value of doing so in this case is nil.   This is the result of our thermal simulations in designing the heatsink.  The reason the few mm on the edge of the spreader are left uncovered is for package fitting. 

I understand the reasoning behind fitting the heatsink inside the case, but I must disagree with it not having a significant value. Mining is all about min/maxing. the heatsink could have quite easily extended the .25 inch (i'm guessing based on this picture) to gain the extra dissipation. The design of the enclosure for the single is absolutely terrible for dissipating heat, causing the fan to work harder to get less airflow. As far as the hack job you have done sanding the chip, here's an article from 1999 explaining what should be common sense.

 I like the singles, and I like what i've seen of the rig box, you guys have done a decent job at creating a product that fills a need in the market cheaply. That being said, your thermal solutions have been quite terrible/sloppy , and all the designs for the rig box are showing signs of the same backwards logic. I understand every startup company has growing pains, and i don't expect you to get everything right the first time, but please stop making excuses for poor designs and start fixing them.
hero member
Activity: 988
Merit: 1000
Has anyone tried some of these: http://indigo-xtreme.com/

I use Cooljag's Thermal Compound (Shin-Etsu x23-7762) on all my GPU's it works far better than Artic or IC Diamond for the uneven surfaces.

Cost shouldn't be a big limiting factor with TIM, if you already paid $600 for the unit and $10/15 difference in better product is a wise insurance investment.
legendary
Activity: 1400
Merit: 1005
So chips are not sanded, it's the heat spreader what we see when someone removes the heatsink...

spiccioli.
The heatspreader is an integral part of the chip packaging, they don't apply it themselves.
... and they should hopefully stop sanding them since we all now know that the chip is an EP3SL150
(just not sure if they are new or 2nd hand)

Correct me if this isn't really a big deal, but aren't rough chip surfaces really bad for heat transfer?

I saw some articles about ppl buffing their GPU heatsinks to a shine prior to installing them.
Yes, but more important is that the surfaces are even.  In other words, you should be able to take a razorblade and put it across the chip in any direction, and not see any gaps where light can shine through.

I'm not sure that it would be feasible to lap the chips as they sit on the board though... so much could get in the way on all the edges, and you don't want to accidentally discharge static electricity to the board while you're rubbing it with sandpaper!  In other words, I wouldn't advise anyone to do it.  But, I would love to see someone try and see what the results are!
hero member
Activity: 714
Merit: 504
^SEM img of Si wafer edge, scanned 2012-3-12.
So chips are not sanded, it's the heat spreader what we see when someone removes the heatsink...

spiccioli.
The heatspreader is an integral part of the chip packaging, they don't apply it themselves.
... and they should hopefully stop sanding them since we all now know that the chip is an EP3SL150
(just not sure if they are new or 2nd hand)

Correct me if this isn't really a big deal, but aren't rough chip surfaces really bad for heat transfer?

I saw some articles about ppl buffing their GPU heatsinks to a shine prior to installing them.
His point is that these surfaces are sanded, but quite roughly, ie, not polished to a shine. This is my Single for example:
sr. member
Activity: 252
Merit: 250
Inactive
So chips are not sanded, it's the heat spreader what we see when someone removes the heatsink...

spiccioli.
The heatspreader is an integral part of the chip packaging, they don't apply it themselves.
... and they should hopefully stop sanding them since we all now know that the chip is an EP3SL150
(just not sure if they are new or 2nd hand)

Correct me if this isn't really a big deal, but aren't rough chip surfaces really bad for heat transfer?

I saw some articles about ppl buffing their GPU heatsinks to a shine prior to installing them.

sr. member
Activity: 448
Merit: 250
...

From a technical perspective, I beg to disagree.

There's a thermal resistance RT1 from the die to the heat spreader, and a thermal resistance RT2 from the heat spreader to the cooler. While RT1 cannot be changed, it is a good thing to minimize RT2. One way of minimizing RT2 is by removing the heat from the whole area of the heat spreader.
So ... that edge is OK (cool) to touch with your finger right? Cheesy
Coz if it wasn't, none of this discussion that saying it doesn't matter would make any sense to me ...

Exactly my point, Kano.
Of course, the ledge that is not covered by BFL's heat sink is NOT cool to the touch.
legendary
Activity: 4592
Merit: 1851
Linux since 1997 RedHat 4
...

From a technical perspective, I beg to disagree.

There's a thermal resistance RT1 from the die to the heat spreader, and a thermal resistance RT2 from the heat spreader to the cooler. While RT1 cannot be changed, it is a good thing to minimize RT2. One way of minimizing RT2 is by removing the heat from the whole area of the heat spreader.
So ... that edge is OK (cool) to touch with your finger right? Cheesy
Coz if it wasn't, none of this discussion that saying it doesn't matter would make any sense to me ...
full member
Activity: 227
Merit: 100
Just unpacked the singles - 1 of 6 sounds like the heatsink is loose -- rattles horribly.

Also - 1 of the singles shows loaded with the 816 firmware?!?

Anyone else get a single that DIDN'T come from the factory with 832 firmware?

For trouble-shooting, you can refer to http://www.butterflylabs.com/faq/
to resolve your throttling issue. Also, for the firmware, you can use Easyminer
to change the version.


Regards,
BF Labs Inc.
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