Question GPU clock fluctuation, causing poor framerates even while overclocking

[Defenestrator IX]

A few months ago, I bought a Radeon RX 580, and for a while I'd been getting phenomenal performance (at least compared to my Radeon HD 7570).
At some point I starting overclocking, getting 60fps (even while not OC'ed) in Far Cry 5 on the highest settings. Well, I've started noticing that the framerate fluctuates, dropping into the fifties, and after looking at MSI Afterburner, I noticed that the core clock doesn't stay solid at 1500MHz like before, it drops into the 1400s. I've also noticed that Assassin's Creed Origins usually sits around 50fps on the lowest settings and 35 on high, even though it's an older game. Even when not overclocking, while running those games, the clock speed will rarely hit 1380MHz, the default clock speed. Some older games, like Skyrim or Dying light, run fine. I have the latest Radeon drivers, but my theory is maybe the issue is my processor. It's a Sandy Bridge i7, so it only supports PCIe 2.0, and my card is 3.0 compatible, but I've done research, and that shouldn't be a problem. But ACO and FC5 both use 50%-80% on all 8 threads, while the older games don't really use much (maybe not bogging it down). Nothing is overheating, CPU doesn't go much above 70c, and under full load (only during benchmarking) the GPU doesn't usually hit 80c (overclocked), it never gets there while gaming.

Any thoughts?

Computer specs:

Dell Optiplex 7010

Intel Core i7 2600

Powercolor Red Devil Radeon RX 580 (8GB)

16GB DDR3 SDRAM

Thermaltake 700w PSU (definitely supplies enough power)

 

[Deleted member 2731765]

Thermaltake 700w PSU (definitely supplies enough power)

Which exact Model is this PSU, Smart 700W 80+ White Certified unit, or some other ? Btw, your current CPU might sometimes create a slight bottleneck, depending on the game being played though.

Also. not all games are going to fully utilize all the CPU cores/threads. AC:Origins is a graphic demanding game though.

 

[Defenestrator IX]

Yes, my PSU is a Thermaltake Smart 700w 80+, but I don't know if it's a "Certified White unit".
Most games utilize all CPU threads, or don't max out the actual cores, and leave the virtual processors to do whatever with background programs. Also, I was thinking the CPU would be the bottleneck, and chance you think it might be the PCIe 2.0 slowing it down? I can probably fix that.

 

[Defenestrator IX]

So I've figured out that my problem is purely software related. I came across a feature in AMD Radeon settings called Virtual Super Resolution. I was able to run Far Cry 5 at QHD, and I was getting only slightly worse performance than when I use my monitor's native resolution, 1360x768. Running at QHD, my core clock was solid at 1500MHz (OC) and 1380MHZ (non OC), and under 80-100% load.

 

[Defenestrator IX]

I checked AMD's website, and there was an "optional" driver available for my card. After installing it, I've been getting solid clock speeds. It hasn't improved Far Cry 5 or ACO much, but I've noticed when I'm in a city (ACO), or anywhere that has lots of detail, my card actually is used less. The utilization drops, the temperature drops, and because of that, the fan speed drops.

Just checked for another driver, and there's another "optional" one from a bit over a week ago.