I am building a PC just for BOINC projects. I already ordered all the components, but just got the news that the motherboard I bought ran out of stock before they shipped mine, and it is now on backorder. So, before I buy something else, thought I'd ask here in case some knowledgeable hardware geek has some insights. :)

The CPU is Intel® Core™ i7-5960X Processor Extreme Edition (20M Cache, up to 3.50 GHz). It does support 40 PCI express lanes.

And, four EVGA GeForce GTX TITAN X SC GPUs for a 4-way SLI.

The motherboard was supposed to be ASUS X99-E WS. It does support 4-way SLI, all x16, thus achieving 40 lane 4-SLI via x16/x16/x16/x16. The only other motherboard I found doing that was ASRock X99 Extreme11, but that is out of stock, too.

Any other X99 motherboards that will accept this CPU and these GPUs are "less than" x16/x16/x16/x16, like x16/x8/x8/x8 (e.g. ASUS RAMPAGE V EXTREME).

I hear that this might cause for latency in gaming, but I have zero interest in gaming. Then the question becomes if x16/x8/x8/x8 would hinder this PC from achieving nirvana in terms of BOINC computations (I support 50+ BOINC projects, and a fair number of them, including GPUGRID, use GPU).

Does anyone know for sure, as opposed to having a gut feelings?

Thanks
Tuna
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I will hold back and not tell you my gut feeling. However, here you go:

https://pcpartpicker.com/search/?cc=us&q=+ASUS+X99-E+WS

I will hold back and not tell you my gut feeling.

And, just found this on Newegg; must have just come in to stock. The same board with the USB 3.1 built-in, as opposed to missing it or needing a PCI card for it. ASUS X99-E WS/USB 3.1 LGA 2011-v3 Intel X99 SATA 6Gb/s USB 3.1 USB 3.0 CEB Intel Motherboard. So, I am going to order that.

Still, if anybody has actual technical info about my original question, I'd love the education.

Thanks
Tuna

I also have no technical info.

But it's really cool that you're making a big investment into BOINC!

Have you considered using this opportunity to return your Titan Xs and replace them with 980 Tis?

They are a smidgen more powerful and will save you in the range of $1,200.

You could make real progress on a second computer with that sort of cash.

And if you've started with one Titan X and are looking for SLI, remember that BOINC projects run individually, so you can pair different cards in the same system.

All my best wishes!!

There's no real difference in the performance between PCIe3.0 x8 and x16.
The WDDM overhead of modern Windows OSes have much severe impact on the performance of high end GPUs.
For example my GTX980 under Windows XP is as fast as a GTX980Ti under Windows 7~10 (you can check it under the performance tab).
I'm sorry to see the large amount of computing power wasted this way.
Linux is as fast as Windows XP.
If you put 4 of those Titan X OC's in a host, it will be hot and loud.
You should use water cooling to overcome this. It will also let you to put 7 Titan X OC's in that MB.
After 5 years of GPUGrid crunching I would not build a multi-GPU system based on a very expensive MB and CPU for GPUGrid crunching. Instead I would go for more inexpensive Socket 1150 (or 1151) MB (for example Gigabyte H81M-S2V) with an inexpensive Core i3 CPU (41x0) and 4-8GB RAM, and a small SSD (60GB would be fine).
These cheap MBs usually have RealTek Network Interface Controllers, which have drivers for Windows XP.
The high-end cards don't have drivers for Windows XP, but the driver's inf file can be easily "hacked" to make these cards work under XP.
You will certainly get to the 1st place on the host's toplist with this PC, until someone will use Windows XP (or linux) on the same hardware. :)

There's no real difference in the performance between PCIe3.0 x8 and x16.
The WDDM overhead of modern Windows OSes have much severe impact on the performance of high end GPUs.
For example my GTX980 under Windows XP is as fast as a GTX980Ti under Windows 7~10 (you can check it under the performance tab).
I'm sorry to see the large amount of computing power wasted this way.
Linux is as fast as Windows XP.
If you put 4 of those Titan X OC's in a host, it will be hot and loud.
You should use water cooling to overcome this. It will also let you to put 7 Titan X OC's in that MB.
After 5 years of GPUGrid crunching I would not build a multi-GPU system based on a very expensive MB and CPU for GPUGrid crunching. Instead I would go for more inexpensive Socket 1150 (or 1151) MB (for example Gigabyte H81M-S2V) with an inexpensive Core i3 CPU (41x0) and 4-8GB RAM, and a small SSD (60GB would be fine).
These cheap MBs usually have RealTek Network Interface Controllers, which have drivers for Windows XP.
The high-end cards don't have drivers for Windows XP, but the driver's inf file can be easily "hacked" to make these cards work under XP.
You will certainly get to the 1st place on the host's toplist with this PC, until someone will use Windows XP (or linux) on the same hardware. :)

Tuna Ertemalp, take you're time... wait til the prices go down. We are in a recession.

Note: Take this advise with a grain of salt, I just enjoy being #1 for the time being. hahaha

Tuna Ertemalp, take you're time...

In a day or two, another machine with GTX 480 will receive its Titan X Hybrid (I found it "open box" on Amazon with some screws missing, and ended up paying only $835 for it!), and I will let it churn exclusively for GPUGrid for a week or two, just to see what it does. Then, it'll go back to serving all projects.

Well, truth be told, I already upgraded a machine with an 8800GT to a Titan X, made it churn only for GPUGrid for a week or two, about three months ago, and it got into top 10 within a week, I believe. Now it is churning for all 50 projects, so it slipped down.