Topic: [Review] Spondoolies SP20 review - A Green miner with a Loud fan - page 6. (Read 20991 times)

I think some air is needed to cool the VRMs on the back of the center ASIC board

careful with that aluminium foil! short-circuit...

Nice work johnyj,

but instead of putting that aluminum block inside the case, what about simply putting a stripe of tape on the holes on the intake side of the case to block air from entering that space?

I'm away from my unit or I'd made this test right now

spiccioli

Mine had none on any on the first SP20 I recieved, I commented on the instability earlier in the thread.

https://bitcointalksearch.org/topic/m.9865070

like what KfC didn't do, you mean?

 

3M's DP460

Edit: The glue has no purpose other then holding the heatsink during shipment.

Only residue, no sign of glue like other chips, no sign of glue on heatsink either  

What kind of glue you are using? I have to get those glue if I'm going to recondition the heatsink, now I'm putting 2 heat pads on each corner to stabilize it

Very unlikely.

The pictures you've posted shows a residue of the glue. Maybe not enough was applied to the specific ASIC.

if it can not go up to speed as the rest, then i guess 99% is because of the chipped corners

Does broken corner affect performance? My broken chip runs at 500 Hz comparing with other chips running at 650Hz

Sexy!

The chipped corners reminds me of amd xp, durons... nice times!

It would be nice to have a miner with lga775(or newer) socket mounting holes! then i can be motivated to repair my cascade system for -80c cooling

When I install those guides, I found out that one of the heatsink does not have those two drops of glue on its side, thus it can be easily tilt or shake by hands. I removed it, cleaned thermal grease, it turns out all of the chip's corner are broken. Without those 2 drops of glue, I can imagine it get knocked by each vibration during transportation



This is a weakness of the cooling system. Like Spondoolies-Tech pointed out, The RockerBox ASICs with the FCBGA package aren't suitable for mechanical stress, since its die directly exposed, and it is small: only 10x11.5mm in size.

The problem is, the heat sink is just too big for the small contact surface of the die, and it has only 2 point of tension. To make things worse, its tension is flexible because of the spring in each screw, this means it will just tilt to any direction and break the corner of the die with the least amount of incaution during install/transportation. So that's why they end up using some glue to permanently fix the heatsink on the board

And, to my surprise, the copper plate is just attached together with the aluminum heatsink with thermal compound without any screw.
They can slide against each other. This means most of the heat will be transferred to the heatsink by this layer of thermal compound, which has magnitudes lower thermal conductivity than either aluminum or copper. When installed, the pressure between them is decided by the spring of those 2 screws, and it is very weak (otherwise it will break the die)

Aluminum sheet guide installed on the heatsink. Since the system adjust the frequency depends on ASIC's temp, which is not visible in the ASIC stats page (only visible once it is above 85 degree), I don't know if this modification works. However, without this modification, the system runs at 5% lower frequency, so I suppose it has some effect

nice catch !

I added some aluminum guides in the heat sink so that the warm air from the first heatsink does not go straight onto the second, but the effect is minimum

Then I noticed that there are 2 large holes before the last 2 ASICs, perfectly suitable for a test of cold air intake modification. I used some plastic foil to wrap the rest of the case, leave these 2 holes open widely by flipping the controller board to the other side



This immediately lowered the temp of the hottest ASICs. As a result, the hash rate jumped: The system's frequency management look at the highest temp ASIC to adjust the frequency of the other chips. Now the back row ASICs can be cooled more, the rest of the chips were tuned up accordingly. And you can see now all the temps are getting close (chip nr.4 is possibly faulty)



It is also worth noting that the front temp on SP20's statistic page is not the ambient temp (I mistakenly thought so in previous posts), it is affected by the airflow speed. With original setup, the front temp reads 18c when ambient temp is 14c (measured by a thermometer in front of the main air intake of the SP20). And in my modified setup, the from temp reads 25c

excellent review and some great tinkering. well done on getting such low w/gh

Made an aluminum block to narrow down the lower channel





Unfortunately the result is worse, temps rose by a couple of degree under same ambient temp, maybe some turbulence made fan spin slower

or set watts lower for them and set starting volts lower for them.

 I am running 5 stacked and 1 on a shelf.


I had  2 ways of heat+noise management.  heavy down clock to 1150-1200gh fans at 20-30%  since they are in an attached garage noise is not a big deal and I can even close the back door of the garage

   or a higher clock at 1300-1350 fans at  50-60% and  stagger the settings.  I have to open the back  door  of the garage for at least 3 hours each day.  and they are a little too loud.   

bottom line 7200gh vs 8100gh.   3900 watts  vs 4775   .54 watts a gh vs  .59 watts a gh 

 and a happy wife  which is very valuable in life indeed.

I have decided to go with the lower clockings for now.

I agree with you, after 3 days of testing, I found out that those 4 ASICs in the back row are much more stressed due to the uneven cooling design of the case, and since the front row of heatsinks totally block the air passage to the back row, there is no easy way to get cold air into the back row without passing through the front row heatsinks, especially the second heatsink near the bottom of the case, since the heat air from the first heatsink has nowhere to go but pass the second heatsink

Some kind of cold air intake duct can be constructed, but that will be very time consuming, maybe only suitable for one or two units