I am using Blender 2.90, but have seen this problem going back to 2.80. Sometimes for no apparent reason, Cycles will render VERY slow on the GPU (2080 TI) using either Optix or Cuda. It’s much slower than on the CPU (9900k). Rebooting (Windows 10) will solve the problem… for a while. I don’t know if this is an issue with Cycles, or with the GPU drivers (I have the latest 442.92 Studio drivers installed).
Is there a way to “reboot” the GPU, without having to completely reboot the computer? Ultimately, having this not happen at all would be nice, but in the mean time, a quick way to fix it would be nice. Anybody ever experience this, or have any ideas?
I have the same drivers and GPU as you do and I have not had an issue. I have only had the pc for about a month and had to reinstall windows as it was blue screening from when I got it, Reinstalling windows fixed that. So I am wondering if it could be an older driver somewhere?
Do you have any other GPU applications installed that have the same issue?
I have the EVGA PrecisionX software loading on startup that sets up a custom fan curve, but I don’t have it set to do any overclocking or anything else. I’ll check for other software that could be “crashing” the card… maybe uninstall PrecisionX to test.
Might be worth a shot, My PC came with some software to control the RGB lighting, I didnt re install that as I am not fussed on the lighting, Have no idea if that was causing my issue.
But it is rock solid now.
Interesting issue. “Restarting” a GPU can be done with Linux (though it doesn’t always work). I don’t know of any way with Windows. For my Windows System to solid I had to do a clean install and limit the apps install to the minimum. Fairly solid for me since doing things that way.
I discovered something about this problem. PHOTOSHOP or LIGHTROOM !
I was experiencing the ultra-slow GPU rendering (and viewport) issue, so I was going to reboot my computer. I had Photoshop and Lightroom both open. I closed them both, then it occurred to me that since both of these programs utilize the GPU (to a small degree), maybe they are causing this problem? I went back to Blender and to my surprise, it was fast again! Viewport and render speeds were back to normal.
To see if simply having those two apps open was the cause of the issue, I opened them again, but rendering in Blender was still fast. So maybe I need to use them both a bit before the issue shows up. Also, I’ll leave them open, and next time I see the issue in Blender, I’ll try this trick again just to verify.
Hi.
Has the problem happened to you with more than one scene or just one scene? Have you tested if slowness always occurs in some frame interval? Are you using Motion Blur?
Just in case you monitor with GPU-z the GPU temperature and vRAM usage when you start having the problem.
I just did some tests… renders were going about half speed. GPU utilization was just a few percent at idle, but 100% when rendering. Both Photoshop and Lightroom were open in the background. After I closed them both, rendering speed went back to normal. The slowdown this time wasn’t as severe as before. I don’t know what that means, but for the second time now, simply closing both of those apps has solved the problem.
In my case when programs are fighting for GPU resources (including Adobe) I found that instead of having them up in the background, minimizing them to the task bar made all the difference.
But the problem is CPU or GPU?
Supposedly you in Windows can set CPU priority to prefer foreground applications. Also individual CPU priorities per application.
I am not sure about GPU.