EVGA 980 Ti Hybrid SLI issue after custom loop upgrade and motherboard swap

What started out as a plan to install a small custom loop to replace my Corsair H110i GT turned into a much bigger project when I decided to incorporate my EVGA 980 Ti Hybrids into the loop as well. I switched from an Asus x99 Deluxe to an Asus Rampage V Extreme, both of which are the USB 3.1 variant. Aside from a motherboard, power supply, case and cooling upgrade, everything else is the same. All said and done, it turned out fantastic with the exception of performance in SLI.

When I test/bench the 980 Ti's individually, they perform notably better than they did with the old Hybrid coolers and run much cooler. When I test/bench them in SLI they don't come close to what I achieved in SLI with the stock EVGA Hybrid coolers. There seems to be a bottleneck somewhere as the cards in SLI are holding their overclock nicely, but I get the same scores at stock speeds and overclocked. When I run tests with the cards configured individually, an overclock results in a substantial improvement. This behavior happens with or without a CPU overclock as well.

I've pulled the cards and reseated them to no avail. I tried 3 different SLI bridges along with testing old and new drivers with no impact. Both cards are installed the recommended x16 slots.

At this point, the only thing I can think of is that it's either a motherboard issue or something with the 980 Ti's changed when I replaced the stock hybrid coolers with EK water blocks.

I'd appreciate any advice with troubleshooting!

Asus RAMPAGE V EXTREME/U3.1
i7 5960x
32 GB Corsair Vengeance LPX
2 x EVGA 980 Ti Hybrid
512 GB Samsung 950 Pro
Corsair AX1500i
Custom water loop with EK blocks for CPU/GPU

Temps when running in SLI?
Have you verified the GPU's are getting 3.0x16 when in SLI via GPUz?

ATMINSIDE said:

Temps when running in SLI?
Have you verified the GPU's are getting 3.0x16 when in SLI via GPUz?

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Temps in SLI are 21/22 at idle and 35 max when looping Unigene Heaven. During a Heaven benchmark, they get to around 32.

I have verified x16 3.0 via GPUz.

It's actually blowing my mind because the GPUs are running cool and they maintain their over clocks in SLI without any gpu throttling at all. I do hear more coil whine now, but I attribute that to the fact that I removed the stock shrouds and replaced them with the water blocks.

Have you reinstalled the driver and picked "clean install"?

Sure have. I even reinstalled Windows.

Motherboard BIOS up to date?

I'm currently using the latest BIOS, which happens to be the one it shipped with.

This is beyond strange. Everything (CPU, Memory, GPUs) is running faster, cooler and very stable with the exception of the GPUs when configured in SLI.

As soon as I completed the build, I put them in SLI and ran a bench. Came up over a 1000 pts lower in Unigene Heaven and a few thousand lower in 3DMark. I then disabled SLI and benched each card comparing them to my spreadsheet of previous test and they were quite a bit higher each.

Even stranger, when I bench SLI at stock GPU/CPU clocks, the scores are more or less the same as when I dramatically overclock both GPU and CPU. The setup is acting as if there is some type of bottleneck.

At this point I'm honestly not sure what's going on... sorry.

Just out of curiosity when you ran them in Sli without them in the loop you were using the Asus X99 Deluxe board? If so assuming you do not have that board anymore to test on, I'm thinking maybe it's an issue with the board.

Mandrake4565 said:

Just out of curiosity when you ran them in Sli without them in the loop you were using the Asus X99 Deluxe board? If so assuming you do not have that board anymore to test on, I'm thinking maybe it's an issue with the board.

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Yes, the cards scored much better in SLI on the Asus x99 Deluxe board. I also lean heavily towards the issue being the board, which really sucks. With the new loop installed I'm going to have a lot of fun swapping boards.

- - - Updated - - -

ATMINSIDE said:

At this point I'm honestly not sure what's going on... sorry.

Click to expand...

I appreciate your help!

It stinks having to swap things around but it seems that if the issue wasn't present before the swap, it may be the board.

Mandrake4565 said:

It stinks having to swap things around but it seems that if the issue wasn't present before the swap, it may be the board.

Click to expand...

I just picked up another ASUS X99-Deluxe/USB3.1 board and I'm beginning the swap.

After digging through the Asus ROG forums, I'm not the only one to have experienced this issue. It's hard to believe that a more expensive board designed specifically for overclocking/gaming would do this. There were a few features of the X99 Deluxe that I was missing so this might just work out for the better.

Well let us know how it goes.

Mandrake4565 said:

Well let us know how it goes.

Click to expand...

We are back in the fight!!!

Board swap complete and it's running better than ever. I am now able to fully see how much the custom loop has improved cooling over my last setup which consisted of a H110i GT AIO and 2 Hybrid coolers.

The benchmarks at the same OC settings are now slightly better than before and I should be able to push it quite a bit further once I'm used to the new setup/temperatures. GPUs on this run reached 31 and 32 and the CPU pegged at 47.

I'm still a little confused about how the Asus Rampage V Extreme was the source of the problem, but I'm glad it happened. The board was the wrong colors anyways.

Thanks for the help guys.

Glad everything worked out for you!!!
It's odd to see the board cause the issue like that, but sometimes things happen that have no rhyme or reason.

Yup glad it worked out and strange indeed.