Topic: First power bill for my 6 GH/s rig - page 5. (Read 10105 times)

Hmmm. How do people drive VW Beetles(real ones) in the summer then?

I would love to have 0 degree air to cool my rigs year round, but I don't have that luxury. I need to find something that will work for me in hot humid weather.

A car with an air cooled engine would stop working during the summer if it became stuck in stop and go traffic.

Analogy fails.

A GPU running at 95C core and 120C VRM isn't going to last long.  A farm with dozens of GPU at 95C core and 120C VRM is going to be a complete nightmare to manage.  You will end up making less than minimum wage dealing with the nonstop crashes, hardlocks, equipment failure, and downtime.   I don't know any serious miner which runs the cards at 95C for 24/7 operation.  I shoot for 70C operating temps.  At 80C cgminer is dropping their clocks to keep temps in line.  VRM are pushed hard when mining.  They tend to run 20C+ hotter than core temps.  None of my cards have seen 95C core and hopefully never will.

*shrug*.  Whatever.  You're missing the point.  An analogy is meant to be just that -- an analogy...  not a perfect comparison of every aspect.  It's done for simplicity in order to get someone to connect with one aspect of the analogy.  By your logic, the only valid analogy to cooling a GPU is cooling a GPU.

Yes, I'm obviously just a troll.    Look at my post history.  I'm an obvious troublemaker.  I try to correct someone's misinformation and that's trolling?  You correct misinformation in many threads, so you must be a troll too.    Your posts are generally informative and logical.  These have been derogatory and angry like you have a grudge.  Yes, feel free to ignore me if your responses are going to continue to be that way.  I'll go back to my 45Ghash of "magical" GPUs and continue to scale it with my air cooled "sorcery".

There is a problem with your well thought out argument.  Most GPU run fine up to 95C.  VRMs, which can sometimes be the limiting factor, function up to 120C.  The delta difference just isn't as big as you think it is.


Now, a video card will almost certainly last longer at 60C than it will at 90C, this is true.  But to make any accurate measure of value you need to look at the cost of the card over it's lifespan in each case and determine if the increased GPU lifespan is worth spending additional funds on cooling.  Then there are other variables, for example you might be better off and end up with lower temperatures AND lower overall cost by using a water-cooling system with outdoor air vs an indoor air cooling system with AC.

I'm done.  You indicated you can aircool at 100F ambient temps.   So yes ambient temp would = 100F.  40F OVER AMBIENT would be (here let me help you)

100F + 40F = 140F.

Keeping the GPU temp below 140F would require a cooling system that can achieve 40 deg F OVER AMBIENT when the Ambient temp is 100F.

It doesn't really matter what happens on the coldest day does it troll?  Since despite 5 posts you don't seem to grasp that I will take it you intent is just to troll and let you troll on.

 In the winter, my inlet air is around 0F (or lower).  My GPUs are regulated by fans to around 160F (71C).  I guess mine are magical because that's a 160 degree difference and I have a few cards that are 3 years old and still doing GPGPU computation 24/7.  I'll just assume that you are trying to say something different here or you are setting some specific value for "ambient" in your head...

You are completely overcomplicating the argument.  The original statement/arguement was that a GPU cannot be cooled with 90-100F air.  I said that the statement/arguement was wrong and silly because a GPU most certainly can if you provide it with a constant supply of fresh air.  You're arguing my side and apparently not realizing it.

I never said or implied that they do.

Agreed.  At only 40F over ambient, the fuel would never combust.    The cooling system could just be stripped out entirely.     Jokes aside, I'll assume you're saying "coolant temperature at only 40F over ambient" because you were apparently quoting coolant temperature before when you used the 200F figure.  If you wanted a vehicle's coolant to run at only 40F above ambient on the freeway, just remove the thermostat.    No radical redesign necessary.  Don't say that I didn't warn you that it'll only burn 5 percent of its fuel though. 

Err...  if that's the case, then everyone who fires up Crysis 2, Furmark, OCCT, or Furmark without manually controlling their fan speed will trash their GPUs.  Most of the recent ATI cards will happily run at 70-75C and will even stay stable to 80C.  The clock throttle on most BIOSes are set to around 90C (194F).  "No more than 140F" is pretty low.  Not only is it low, but it's lower than the manufacturer sets the auto-fan profile to.  They are certainly designed to run hotter.  Longevity is a different argument altogether.

Are you sure that you're not confusing the term "over ambient"?  This applies to water coolant temperature, but doesn't apply to air cooling (or air cooling a radiator) in the way that you are stating...  Engineers don't design an air cooled device (like a video card) to run at a certain temperature over ambient.  They design what temperature/temperature range the device should run at and then specify the minimum/maximum ambient temperatures that will allow it to stay within the set thermal threshold.

lawl

but more on topic = Invest slowly and build your farm over time. Huge bitcoin mining investments usually fail (Going off past posts I've found here). Slowly working your way up helps you learn alot of things you'd never consider otherwise, plus if you work up over time it's much easier to deal with anything that might go wrong.

A long winded nothing and you missed the only point.

Car's cooling system can effectively dump the heatload because a car can operate at 200F.  That is 100F OVER ambient under worst case scenario.   If a car's cooling system had to keep car's internal temp at <140F then a car (as built today) would be insufficient to operate when outside temp is 100F+.  If a car could operate effectively at 300F it would need a SMALLER cooling system (relative to heat load) to keep temps <300F when ambient is 100F.

Car = 200F operating temp = 100F Delta T to ambient*
GPU = <140F operating temp = <40F Delta T to ambient*

On edit:
* further and likely unecessary clarificaiton because sveetsnelda is either an idiot or a troll ...

The fact that a car can operate (at 100F over ambient) doesn't prove anything.  A nuclear reactor can continue to operate at 600F over ambient that doesn't mean a water cooled rig that keeps a GPU at 600F over ambient will be effective.  Why do reactors run at 600F?  Because the cooling system can be smaller/cheaper/more efficient than if it needed to operate at 500F, or 200F (car), or 140F (GPU).

40F Delta T is not much to work with.  The smaller the Delta T the more volume necessary to transfer the same amount of thermal energy and the same surface area.  If you can keep an entire farm stable 24/7 with 100F input air temps well you are better than most.  My guess is you 100F temps are with low humidity? Still your stupid car analogy is just that ... stupid.

The analogy is far from "broken".

The car analogy wasn't meant to be overly technical or precise.  Judging by your posts, you obviously understand the basics of thermaldynamics.  My arguement was with someone who apparently does not.  If my argument was with someone who did, no broad analogy would have been needed.

That being said, everything in your post just explained exactly why my internal combustion engine analogy makes perfect sense.  He said something along the lines of "Video cards are hot.  When the air temperature warms up, enough heat can't possibly be removed".  My response was "Yeah?  Engines are hot too and we keep them temperature controlled in the summer just fine."

Yep.  Most modern automobile engines are water cooled for many reasons...  the biggest of which being that the engine is crammed into a compartment for aestetics and protection.  Noise and emissions are up there too.  I don't plan on putting my GPUs in a case and rolling them down the freeway anytime soon though.  I also don't burn hydrocarbons in my GPUs, so I don't need to worry about NOX levels.    Another reason they're water cooled is because it's easier to regulate the temperature to tighter tolerances than air cooling (using a thermostat).  If an internal combustion engine runs too cold, performance/efficiency suffers heavily.  There are plenty of modern air cooled internal combustion engines out there as well though.  I could give a pretty good dissertation on the subject because I study/build/repair/modify gasoline engines.  It's not very relevant to the discussion though.

Combustion engines produce substantial heat.  GPUs produce substantial heat.  Both require heat removal to prevent failure and both have very large temperature deltas compared to ambient temperature air.  Yeah, I see they are both completely unrelated.

Can you please stop using the broken card analogy.  You may be right but your car analogy annoys the every loving shit out of me. 

Car operating temp is ~200F (90C).   The higher the heat differential the easier it is to move heat.  So car @ 200F and ambient at 100F = 100F difference.  You can accomplish same amount of cooling with a lot less airflow than trying to keep a GPU @ 60C/140F with ambient @ 100F = 40F difference.

Also car engines are watercooled for a reason.  It moves the heat into a radiator with massive surface area. 

So in summary
* the hotter the device is relative to ambient = easier to cool
* the larger the surface area is relative to ambient = easier to cool
* the higher the airflow = easier to cool

Just because a car can be kept "cool" (when cool = 100F over ambient temp) doesn't mean it applies to GPUs.

So please stop with the car analogy nonsense.  It doesn't help your case.

Of course it is.  ...just not when you cram everything into a 1U case and flow hot air from one component to the next.  Again, if this statement were true, we'd all have to shut down our cars in the summer.

Oh yes.  Complete lack of knowledge.    I've made national news for my "lack of knowledge" regarding hardware.  If you took thermodynamics or fluid dynamics classes, you obviously flunked.

Funny you should mention it...  I actually do.    I work for a fairly large enterprise.  Commercial data centers generally have other restrictions imposed on them or have other design concerns to work around.  I certainly have a bit more freedom with my home rigs.

My 45 Ghash of equipment is currently putting out about 21.5KW of heat and they are crammed together in a more heat dense fashion than most data centers would ever allow (Amazon's EC2 possibly being an exception).  I'm currently cooling everything with a standalone small household fan for each rig and 2 window fans.  It gets into the high 90's and occasionally the low 100's here in the summer (desert climate).  I used a small evap cooler last year during the summer because my current layout ends up recirculating a little of the air from one rig to the next.  With the right building design and powerful fans, I wouldn't need an evap cooler at all.  The fans on my reference cards are never running above 60 percent (right now, most of them are in the low 30's because the inlet air temp is still so cool).

In two weeks, I'll be migrating all of my rigs to a dedicated building in the back yard.  In the summer, I won't need evap cooling if I want to run the fans a little high because I'll be exhausting ALL of the hot air and routing it properly.  Can't wait to "kill a lot of hardware"!

The key to the problem is the temperature delta. Sure ambient might "only" be 43 degrees C, but is that low enough to keep the server within tolerance after adding all the heat from the CPUs, RAM, SCSI cards, etc? Usually not.

That article was more theory than proven practice.  They only had 5 servers...in a tent, using way less power than something loaded with GPU's.  Lets try to scale that up and see what happens.

There are *very* few places on earth where you can get away with cooling a dense DC with just ambient outside air.  Trust me, Google and Facebook have looked very hard and written great articles about it.  In the end they are forced to put DC's in places where the local temps get too hot, within the course of a year, to work with just outside air.  We aren't talking about running a bunch of mining rigs just in the dead of winter.  And when I say too hot it's not like I'm talking 135F.  They end up using some form of energy input into the system to get the temps down.  You would be surprised what Facebook can do by misting water into their fresh/recirc air.  But that still takes power to pump!  Not to mention the cost of the water!

And yes, it just so happens that I have had to design data centers in my career.  Including power and cooling for them!

Where does it come from?  No, not your air conditioner - You open... wait for it... Another window.
Hot enough to kill the whole idea?  Seriously?  Do you folks live in Death Valley?



I don't design datacenters for a living, but Microsoft has a few guys you might need to set straight:
http://blogs.msdn.com/b/the_power_of_software/archive/2008/09/19/intense-computing-or-in-tents-computing.aspx
Let me know how they respond to your concerns.   

I'm glad you don't design data centers for a living.  You would kill a lot of hardware with your lack of knowledge.

Exactly.  This is why internal combustion engines in our cars stop working in the summer time.   ...no wait...   

You guys realize that 110 degrees Fahrenheit is "only" 43 Celsius, right?  That's still over 30 degrees lower than the temperature my GPUs run at.  With enough airflow, the heat will certainly still be removed so long as the heat isn't recirculated through the cards.

I was about to post the same thing, lol.  I don't care how much air you can exhaust out your window from your mining room, it comes *IN* from somewhere.  And in most locations the ambient air temp outside is going to get hot enough to kill the whole idea of just using a fan.