View Full Version : About power consumption and cooling

06-29-2013, 07:18 PM
Hi all,
i discovered with surprise that our 5 workstation (standard I7 + standard Geforce - not GPU beasts), and two LCD monitor for each machine, take about 1600W when CPUs are running 100%.
Our small farm in full run - eight machines, six I7 (two 990 extreme, other 960/70) and two dual Xeons, no monitor - takes 2300 W.
Since we need to grow farm and upgrade workstation, this is starting to become an issue both for power consumpion and for room cooling (BTW farm is in a separate room).
What can i do to optimize at best both these aspects ?
Are latest CPUs are more power savvy ? I'm also thinking about selling farm machines and stepping up to a rack system, it should consume less (assuming i get same CPU power).
About cooling, is water cooling or peltier cells a good way to keep machines cold without having to run air conditioning so hard ?

Thank you in advance,


06-29-2013, 07:51 PM
When I have everything on, 6 PCs (3 boxes are dual CPU), Mac Mini, 2 x30" & 1 x 24", & all the PCs rendering. My EvolutionS 3.0 kva UPS shows about 2500 watts load. About 20 minutes back up if I have a blackout without killing the batteries.

All the computers where possible have low power Noctua fans. (also put Noctua fans in the UPS, 3 x 80mm)
Monitors are all calibrated to 90 cd, you will save some power here!

Because the computers have Noctua towers I have no overheating issues. In summer they are quite happy. Only the E5335 has a problem as it is stuck with the Intel server fans on the CPUs which scream their heads off in the heat, even after cleaning the copper heatsinks. This box is so old it is not worth spending money on it. But the rest of the fans in it are Noctua, squeezed into every corner & onto the RAM.

I would stick with the cheapest cases you can buy, stick a 3930 in it with a tower HS on top or water cooled. The CPU has a good frame rate/$, you can leave out all the graphics cards & DVD as they are not needed, the tower HS will get the heat off the CPU even if the room is fairly hot & the computer will not overheat. Also you won't have to wear earmuffs if you need to go into the room.

The room will need good ventilation, preferably with some sort of air filter to stop the dust. Also streamline airflow through the room, in at floor level & out at the top preferably out another wall or window. Also be aware of air pressure that might slow the air exiting the room. Even setting up some simple air deflectors within the room to get good air flow does wonders.

If you can't ventilate the room then you need an air conditioner, but that adds to the power bills.

I would try as much low tech, & passive, & sensible placement first & see how it goes.

06-30-2013, 04:51 PM
thanks for the advices, i'll check Noctua tools. Both main work room and farm room have window, but not on two opposite sides (just on one wall) so trans-ventilation is impossible. anyway i can try improving PC placement so they all push hot air in one direction only so i can create some flow, instead of a turbulence like now.
I was also thinking about remote farm - putting farm elsewhere and managing it online - but i think it would slow a lot everything, since web connection here is not that fast by default, and hi-end connections are quite expensive.


07-01-2013, 02:39 AM
Both main work room and farm room have window, but not on two opposite sides (just on one wall)

That's better than what some have to work with.

Get an inline duct fan or something with bit of pressure. I stuck one of these (different brand) in some air-con ducting to give it a boost. 200mm diameter 70 watts, probably good enough pressure for what you need. Not too noisy, stick a bit of insulation around it.


& as you have mentioned.... good placement will do wonders & not cost anything. Just make sure you are not sucking the hot air back into the room. You can test air flow with some incense sticks as long as smoke detectors don't go off!

Good placement & a duct fan should will solve most problems cheaply.

07-01-2013, 02:51 AM
interesting and very analogic :)
I'll try asap.

07-01-2013, 04:10 AM
I bought peltier (not to cool computers, but diffusion cloud chamber), and can say you it's going from +20 C to some minus degree in a few seconds after plugging it to 5 VDC battery. Manufacturer website says it can get 68 C temperature difference. So from +20 C, we should get -48 C. But you have to have plug to it piece of metal/radiator, on hot side. The bigger piece of metal, the lower temperature you will get on the cold side. Heat is flowing preferably through metal, than air, so piece of metal can be wicked bended, and then put to f.e. water, or maybe even real fridge. It cost 9 usd.
Peltier can be plugged one on top of another, hot side to cold side of another, in layer. Bigger (more expensive) dimension on bottom. Then the most bottom connected to metal/radiator.

07-01-2013, 04:35 AM
I bought 4 x 40mm peltier devices years ago for fiddling around with/refrigeration. They are not the solution for computers. power hungry & condensation issues, & you still have to get the heat away from the peltier itself with even more efficient heatsink.

A tower or water cooled HS is easy to install, no condensation & will get more than enough heat off a 130 watt CPU even in a hot room & still be quiet. My dual W5580 box, each CPU is 130 watts (my E5450 is a similar setup but with smaller towers due to space & almost as quiet). The heat pours out the back of this box. The last system fan (the black one behind the Noctua) rarely increases speed, even in a warm room.


If you look at the second CPU it's copping all the warm air from the first CPU. I've had this box render days on end in Sydney in summer and the only thing stressing out from the heat is me! The computer is still quiet.

07-01-2013, 07:25 AM
If you really want to try something 'new' cooling wise: http://www.grcooling.com/

But yes, cooling is a problem when you don't have a well designed server/farm room. We have a server room designed for very old hardware, and our small farm (Xeon E5 series) chews through 11K Watts of power each hour when rendering, which produces a LOT of heat, and the server room cooling is barely able to keep the room properly cooled.

07-01-2013, 08:26 AM
We have 2 meters, each has 415 volts 3 phase 20 amps for instantaneous hot water. Now if only I could convince the other have to have cold showers! I would have 50kw for a render farm! & the power bills to go with it!