How cool is the room? What is your target temp for the CPUs? You could spend $120 at WalMart for a window AC unit, then close the door to keep the room cooler than the rest of the house.

Thanks for your contributions

Thanks to all

@B2I - I'm working hard to reduce the electicity bill, so while a good idea, A/C is not an option.

@Tomahawk4196 - Just for reference, the room is currently 25.1C at 16:00 BST (UTC +1)

@SuperMecha - Yes, but doesn't undervolting reduce performance too?

Sorry for the confusion, when I suggested using AC fans I meant Alternating Current (plugged in to the wall socket). these fans draw very little current and add no load to the computers power supply.

As for undervolting, it can reduce current draw and heat and may appear stable but monitor your results stats closely for increased errors and invalids. I attempted a custom build once that would produce the most possible PPD for the lowest watts. I bought a 2600s cpu, small SSD and 1.2 volt memory and tweaked it lower in the BIOS. It seem to work well but I began to find it blue screened once a week or so. I gradually bumped it up in volts until it stopped blue screening but still threw more bad WUs than my other machines. After months of tweeking it is putting out about 4500 PPD and drawing just under 95 Watts. But I have to limit CEP2 to one work unit at a time or I still get errors.

After years of hot rodding cars, motorcycles, handloading hotter than factory ammo, and tweaking computers, I have come to a profound conclusion: the factory engineers are usually smarter, have better equipment and more time than me when they set defaults. for all-round performance under widely varying real-world conditions, stability, and longevity, It is hard to improve on their settings. However, it you want to optimize for a specific set of conditions, improvements can be made.

My 62 Chevy II with a .060 overbore, 12:1 compression ratio, full race cam, solid locked rear axel. 5000 RPM stall torque converter and 4.56 gear would shut down any local challenger in 1/8 to 1/4 mile drag racing on a cool night. but try taking in on a date or drive in the country and court disaster. Same goes for my i7 2700K overvolted to the max, overclocked to 4.7 GHz, 3 delta fan D14 running full blast, in a cool basement, after market chipset heatsink with a wallmart window fan 6 inches from the MB in its caseles layout. It cranks out PPD like crazy, but try to plug in monitors, keyboard, mouse, optical drives, and use it to check email, rip a CD, and surf the web and run MS Office and be prepared to see the blue screen.

But for guys like me, (and sound like you) this is what fun is all about. good luck on your quest and keep us informed.

@B2I - Oops! we just refer to that as 'the mains' or main electrictricity or something else similar.

On the subject of undervolting, as I mentioned above, I'm going to give it a try over the weekend, see what results I can get and see if the PPH is stable as well as the OS - W7/64.

I run all machines (except this one) 'headless' using either RDP or VNC to connect across the 1Gb LAN I've setup. works very well, just uses lots of power...

As you probably know, RDP causes the GPU to die so VNC allows the connection and the GPU to work.

I hear what you are saying about the default settings, I've used the built in O/C options to run some of my systems faster, with good results. My 7970's are currently running at 12288 GFLOPS

06/08/2013 22:09:41 |  | CAL: ATI GPU 0: AMD Radeon HD 7900 series (Tahiti) (CAL version 1.4.1741, 3072MB, 3032MB available, 12288 GFLOPS peak)
06/08/2013 22:09:41 |  | CAL: ATI GPU 1: AMD Radeon HD 7900 series (Tahiti) (CAL version 1.4.1741, 3072MB, 3032MB available, 12288 GFLOPS peak)

this is acheived by using the AMD vision Control Centre & it will go higher! I may see just how high they will go and still be stable.

Undervolting will be a new challenge!

I'll let you know what results I get...

Many thanks for the comments and clarification

I take it back, the system just crashed running 4 Poem GPU tasks at settings last mentioned above!

I've reverted to 1200 clock & 1550 mem resulting in the 12,288 Gfs originally mentioned.

Strange how you can 'stumble' on the optimum setting without any testing, I just Oc'd the GPU's to that setting and it worked, it appears to be the best for both Milkyway and Poem to work really well.

I guess I'll just leave it alone now.