TR Forums

Hi,

I get my hands on a lot of PC parts, and I've recently upgaded my platform to an ASUS Maximus VII Formula Z97 board + 4790K, which is really nice. However, when trying to use multi-GPU setups (two cards, 8x each), I have a very interesting and elusive problem.

Okay, here it is. Running a pair of GTX 670s in SLI...

In Unigine Heaven and 3DMark 11, with heavy tessellation, I experience really bad microstutter. During this stuttering, I observe the GPU usage dropping to ~40-50% a card, and the frame-times going through the roof. The FPS plummets, levels out, plummets again, the usual, but severe. (This is actually the cause of my previous post about R9 290 crossfire utilisation, but I'll come to that in a sec...) Also none of these problems occurred with my previous motherboard +CPU.

I have noticed that reducing Tessellation, during the scene in which the stutter occurs, completely fixes the problem. It's re-producible to the point when I can literally toggle the GPU usage drops with the Tessellation slider. Without it, it's silky smooth. With, the GPU usage is barely above 60% a card, and I'm pretty sure a 4790K is not going to bottleneck these cards, since my 2600K had no problem.

I've tried everything I know to solve this issue. It's driving me crazy, and I've gone to extremes. I've completely formatted my system and re-installed the OS, tried different drivers, and even different video cards, to absolutely no avail.

It occurs on GTX 670 SLI, GTX 580 SLI and from what I can tell previously, on my 290 Crossfire that I had access to a while back, but not any more.

It's massively reducing my benchmark score in both the above apps, but from I can tell, doesn't actually effect games that much. Metro 2033 Redux is smooth, and so are the regulars I play, such as Warframe.

It can't be driver or software related, surely? I've completely nuked the OS and EVERYTHING on the drive(s) and started a fresh. I've even re-flashed my Motherboard BIOS a few times to no joy. Could a motherboard hardware problem be causing this rather specific issue? Maybe tessellation puts a certain strain in the PCIE link that causes the issue? Any ideas, I'm completely stumped short of contacting ASUS technical support over this.

Thanks

Obvious point is that you're having an issue with benchmarks and not games. As long as it's fine in games, I'd ascribe the problem to drivers, at most.

morphine wrote:

Obvious point is that you're having an issue with benchmarks and not games. As long as it's fine in games, I'd ascribe the problem to drivers, at most.

That's what I thought at first, but I've re-installed the entire OS to attempt to fix it, and I'd really like my system to achieve its full performance in the above benchmarks, so any ideas?

Thanks

I didn't mean problems with your install, I meant a driver bug in general.