MOBO and Processor for a 2 GPU setup

Hi all,

I am in the process of building a machine GPU computing.
The idea is to have 2 GPUs(Titan Xs or GTX980s, depending on my future budget).
I guess I could save a bit by getting a 79 (instead current 99) system.
I am thinking of:

  1. Intel Core i7-4820K.
    Does it make sense to pay more for 3930 or 3820?
  2. Asus X79 Deluxe MOBO
    or Asus Rampage IV Extreme? Or should I get a better one?
  3. 32GB of memory.
    Do you think such a machine would work well enough?
    Any suggestions would be appreciated, as this is my first build.

[Caveat: I haven’t custom-built a system in many years, and am not familiar with the components listed]

It all depends. Whether this combination would work well is primarily a function of the application(s) you plan to run on the machine. For example, by choosing an X79/IvyBridge-E combo you are missing out on AVX2 and DDR4 support available from a X99/Haswell-E combo, but your are also saving significant amounts of money. Depending on the application, it could make sense to spend the money saved on a good-sized SSD.

For most purposes, a quad-core CPU partnered with two GPUs should be more than sufficient. The specified amount of system memory looks right to me (my personal rule of thumb is system memory ~= 4 x total GPU memory). I would suggest getting an 80 Plus Platinum PSU for a system like this.

For X79 I built 3 PCs with these exact specs and have been very happy with them:



and then two EVGA GTX 980 superclocked ACX:

add 32 GB of RAM and a Samsung SSD and you are ready to go. That setup has been pushed hard and had no issues, other than PC case fans going bad.

For X99:

and most important for a dual GPU setup, Do NOT use the ‘recommended’ Intel i7 5820K CPU, as it only has 28 lanes. The 4820 has 40, and in order to get two GPUs at full PCI-E x16 (32 lanes) you need more than the 28 lanes in most newer CPUs.

If you are going the X99 route then the only real option is the i7 5930k (40 lanes) which is rather expensive but one of the fastest CPUs available:

The GPUs are the core of my application (deep learning). That’s why (and the 28 lanes of Intel i7 5820K CPU) I decided to go with the X79 option. The i7 5930k is just too expensive for me (though a computing monster). It seems that the advantages of X99 are not so important to me. Thanks for the suggestions.

Is ASUS Sabertooth better than Asus Rampage IV Extreme (or BE)?
I was a bit nervous by the amount of problems and notorious ASUS customer service.
I guess I’ll have to bite the bullet lol, as there doesn’t seem to be anything else that fits the bill.

I guess the EVO 850 should be fine? Or some other series better?
I’ve chosen G.Skill Sniper Series DDR3-1866.


I know, but thanks for the heads-up. This is the main reason I am going with the X79 and 4820K. I would have snatched the i7 5820K right away if only it had 40 lanes.
Thanks and cheers.

CudaaduC, I saw you asked a question about 4 GPUs. Did you manage to run 4 GPUs on a single MOBO?
Did it work well? Could you tell me a bit about the setup? What MOBO? Thanks.

I use the Samsung EVO SSD.

That X99 motherboard will handle 4 GPUs with one CPU, but even with a 40 lane CPU the PCI-E 3.0 will be x8 for each. If you really need to get more than 2 GPUs in the same PC then a 2-in-1 GPU like the Titan-Z is the best option. Of course assuming you need the optimal host-device device host copy bandwidth.

Never had any problems yet with those ASUS Sabertooth MOBOs, and they have a 5 year warranty. So I have not had to deal with their customer support yet, which I probably deserves that reputation.

Just built this X99 system with 1 GTX 750ti(for display),2 GTX 980(for computation), Intel i7-5930 3.5 Ghz, 1 TB Samsung EVO SSD and 64 GB DDR4 RAM.

Unfortunately the PCI-E 3.0 configuration is x8, x8, x16, even though one would think with 40 lanes it could go x8, x16, x16.

The intent was that there be a GPU set the display which would not ‘lock-up’ if two GPUs were being used to run simulations. That works but would love to get both GTX 980 at x16.