RX480 core clock fluctuating, causing stutter

Feb 8, 2019
Over the past year or so I've been having a stuttering issue on higher spec games. There was no significant event that caused it to start, and my computer has been through several reformats and driver reinstalls which have not solved it. I got the 480 in July 2016 and the only hardware change since has been upgrading my RAM last November(which made no difference to this issue).

An example of it is here, on an ultra settings Heaven benchmark run: https://www.youtube.com/watch?v=Snj1N6DQe74&feature=youtu.be

This sort of rhythmic stutter has popped up in a variety of games(HITMAN™, Ghost Recon Wildlands, Mutant Year Zero, AC: Origins) and in some cases can be gotten rid of by turning down the graphics. Vsync and RivaTuner locking to 60 can help as well. Sometimes a few tweaks will do the job(Hitman), sometimes the issue is still there on low(Origins). The issue used to be worse when I was on Windows 10, I'm now back to 7. Now that I'm sick of working around it I've been looking into it and noticed that the gpu core clock is all over the place and I believe that's what is causing the issue .

Here's an image my GPU-Z Sensor log when running the same benchmark this morning: http://prntscr.com/midrur
Columns are time, gpu core clock, gpu mem clock and gpu temp. I'm stumped as to what is causing the issue is here and I don't have access to another GPU to see if it's the 480 that is causing this. On rare occasions my PC does turn itself with with a loud WOOSHing from some fan in my PC. I'm not actually sure which fan is going into overdrive though, but this only happens rarely and only when playing games. I was only ever to reproduce that reliably last year when playing Pro Evo Soccer 2018, when my PC would turn off with the fan going mad about 66% of the time when getting to the half time menu.

Any chance of some experienced eyes being able to figure out what exactly is the issue here?

Intel(R) Core(TM) i5-4690 CPU @ 3.50GHz

Radeon (TM) RX 480 Graphics 8GB

16 GB

Microsoft Windows 7 Ultimate Edition Service Pack 1 (build 7601), 64-bit

SuperFlower Golden Green HX 450W "80 Plus Gold" Power Supply

Asus H81M-K Intel H81 (Socket 1150) DDR3 Micro ATX

May 10, 2019
I've been having similar issues with my RX 580. AC: Origins runs terribly even on the lowest settings, and some other games like Far Cry 5 have slightly lowered framerates (50s). And MSI Afterburner reports that my core clock is inconsistent.