Hypothetical question: if I would like to build a "cheap" but efficient CPU/GPU folding box ... AMD seems the way to go based on money required for Xeons.
What AMDs would make bigadv with solid PPD result.
Plan is : a 2p or 4p motherboard with enough PCIe slots to also do GPU folding beside CPU; a "One size folds all" approach.
But I'm an Intel guy and severe confused with AMD naming conventions and slot types. Need help to wrap my brain around. What AMD CPU in what socket ?
thanks to the experiments by the folks over at [H] the consensus seems to be that CPU/GPU folding in the same box is a no-go; the GPUs will take enough resources that the CPU PPD takes a huge hit. (because QRB with anything is non-linear and anything -- like a short power outage -- that increases the time to complete a WU really affects your points in a bad way)
somewhere in this thread:
http://hardforum.com/showthread.php?t=1762504&gpu
AndyE talks about using the cheapest low-power Intel processor (Celeron G1610 -- 55W and $50 here) with a 2 PCIe board (best stability) and 2 GPU cards. I followed his advice and that's what I'm running.
I will confirm that it does work nicely. I tested my 660ti in the rig for power -- 170 W while folding; the nVidia cards use more CPU resources (basically soaking up 1 core) than the AMD cards. Then popped the same card in a different rig with an AMD Phenom II 965 BE (125W) and saw 235 W on the meter! So definitely worth getting a low-power CPU if you're going to drive GPUs.
as far as AMD rigs go; unless you have the "good" chips then I'd say forget it and stick with GPU folding. I have a 4p with the base model 6128 chips -- 8-core and 2.0 speed; and I barely finish the toughest bigadv WUs (8101) under deadline and make fewer PPD (like 90 K PPD) than my rig with 2 AMD 7970s! (the AMD 7970 GPU folder draws 330 W when folding for about 180 K PPD)
and the AMD 4p rig draws 525 W so to use far more power for far fewer points is really, well, "pointless"!
not to discourage you, of course, it's still fun but the AMD rigs are, well, pretty single-purpose where at least you can sell the GPUs on the open market if you want to upgrade or need the money or whatever. (when I bought my 6128 chips they were $75 each and now they're about $75 for four!)
twoodcc can let you know what his experience has been -- he's got better chips (and lower power too! -- look for the ones with the suffix HE or high efficiency) so he gets way more PPD. As you've noted, if you're going to go the 4p route, the AMD rigs have the low initial cost advantage vs the Intel rigs, but take more power so over the long run... (bearing in mind that we never know what Pande group will do with their WUs and points)
have a look at what others are doing and then send over some questions!
whatever you do, have fun!
