Upgrading Core 2 Duo System with 2 GPU Cards

[Nert]

I recently added an EVGA GTX750 TI graphics card to my aging Core 2 Duo system. I'm shocked by the difference between GPU points per day versus the points per day for the Core 2 duo.

Intel Core Estimated PPD: 1186 (only using 1 core)
GPU Estimated PPD: 26,820

Here's my system:

Processor: Core 2 Duo 2.4 GHZ
GPU: EVGA GTX750 TI
O.S: Windows Vista (32 Bit)
Motherboard: Asus P5B Deluxe
Memory: 4 GB
Power Supply: PC Power and Cooling Silencer 750 (750 Watt).

Based on the performance discrepency, I am considering adding another GTX75 TI to the mother board. I understand that EVGA cards require one CPU core per card, so I'll need to use the remaining Intel core to service the second GPU instead of to directly folding units. I think this will be a good move from an efficiency perspective since my contribution will be more than 20 times greater than if I use the Intel Core for folding. For $160, I can contribute a lot more and possibly save on some electricity costs because of the efficiency of the GTX 750. All this without having to build out a whole system. (Other than the Folding component, the system is more than adequate for everything else that I do.)

I'm a little concerned about this card not being able to process 17 unit right now, but I'm hopeful that the problem will eventually be resolved. Do these steps sound reasonable ? Have I missed anything ? Does abandoning the INTEL processor affect the science in any way ?

Also, when the Intel cores are "servicing" the GPU(s), how much CPU resources are used ? Does this max out the Intel chip ? Right now the Intel is 100% utilized, and that would be fine going forward. I'd just like to get some idea about what to expect after I make the change.

Thanks for your help.

[davidcoton]

Your basic observation is good -- GPU folding is much faster (and power efficient) than CPU folding, particularly on newer cards and particularly on nVidia Ti models. This is reflected in higher ppd.
Of course there is a downside for CPU-based projects -- if everyone loads up with GPUs and stops CPU folding. Probably not an issue yet but only PG can tell us when the CPU folding rate has dropped too much. This may have been one of the issues behind the announced end of the BA experiment -- intended to release fast CPU hardware back to general CPU folding.
AFAIK, it is only Core_17 ( and then only on nVidia GPUs) that requires a whole CPU to support it, so Core_15 should co-exist with CPU folding. Also, the suspicion is that most of the time the CPU is just in a polling loop, not doing any real work. So it is quite possible that one CPU core can support two nVidia GPUs on Core_17 without any significant loss of performance, though I have not tried it. If you go that way, try it and let us all know! It may be necessary to set core affinities to keep the right process on the right core.

David

[Nert]

David,

Thanks for the reply. I don't think that I will be adding the second card in the immediate future. I was initially very excited about the prospect of adding it and making a bigger contribution immediately. In fact, I had the card added to my New Egg shopping cart. Before I pulled the trigger I did some more reading and decided to delay for a while. The thread titled "Future 17 WU" in "GPU Projects and FAHCores" convinced me that it's best for me to wait for the dust to settle. Since Core_17 units cannot run on Windows systems with the Maxwell architecture and Core_15 units are End of Lifed, I expect the supply of units that I could fold on the new GPU (Core_15) to eventually run out. I can't know when that would happen, but I don't want to be in the position of buying a new card and then not being able to use it to fold. Since my first card is also being used for normal Windows stuff, it doesn't matter that much if I couldn't fold on it for some reason. It would matter if I bought a second card but couldn't use it for FAH.

So, for me, I'll delay for a while. I'll be jumping in with a second GPU after all of the uncertainties are resolved.

[OzPapaSmurf]

I have an i7 2600K @4.2ghz and now, 2 GTX 660 Ti cards as of yesterday. I haven't had time to check out how things are going just yet but it sure sent the temps up.

[Nert]

OzPapaSmurf,

That sounds like a terrific set up. It really is amazing what happens to the temps after the system starts folding. FAH is such a fascinating and worthwhile project. I bought into it a long time ago. I can't remember what I started folding with, but I'm sure that the processors didn't have more than one core at the time. I love the notion that my system (small as it is) makes a contribution 24x7, and that the contribution might eventually have a positive impact on some really nasty diseases. That's what drove my decision to eventually add a second GPU.