Sapphire 7950 - flickering lines only when downclocked. Normal?

[MehraMilo]

I think a bad cellphone camera video speaks 1,000 words here. (I apologize in advance for my complete inability to hold a camera steady.) For best results, put the video in HD and pay attention to the left-hand side of the screen, especially around the 00:17/00:18 mark.

I have a four month old 7950, and it's been doing this from basically day one. At idle (300/150 clocks) it works fine. At 3D speeds (850/1250), it works like crazy. But when it downclocks from 3D back down to those idle speeds, for ~30 seconds, I see those flickers on my screen. They can vary from barely noticeable to pretty blatant and annoying.

When I first noticed this I checked the monitor cables and made sure they were secure, and even tested on a different monitor--no change. Tried rolling back to 13.4WHQL via clean install; no change. (I'm currently on 13.9 WHQL.)

The "fix" I've found so far has been to enable AMD Overdrive, which puts the 2D/idle clocks at 500/1250. When the card shifts from 3D speeds to those clocks, no flicker. I can also then toggle Overdrive off, and the card seems to go from 500/1250 down to 300/150 without any noticeable flickering.

My incessant Googling has turns up threads like this one, which mentions flickering as a common problem with 79xx cards with too low idle speeds, which would fit with what I'm seeing...but it seems like most people experience more full screen flickering rather than what I'm seeing? And constantly at idle speeds, rather than just when the card is downclocking?

tl;dr: do I have the "super-low idle clocks" bug, or is this something else I need to be concerned about? Thanks in advance.

Other system specs:
i5-3570k
Gigabyte Z77X-UD3H motherboard
16GB DDR3 RAM
850W Corsair PSU
Win 7 x64

Edit: Should add that I've never overclocked, and I have hardware acceleration turned off for Flash and Firefox, so when I'm just browsing the web/watching YT, etc., my GPU stays at idle rather than shifting clock speeds constantly.

 

[busta_cap]

I've had the Sapphire Radeon HD 7950 3gb for a few months now and I've never seen that issue. I have used the MSI Afterburner and Sapphire Trixx utils to do a mild overclock on the GPU (something like 10-15%), but I didn't see that problem even before I OCed it.

 

[ikuto]

You need to bump your idle minimum voltage to something a little higher. For instance my 7950 was at 0.950v idle and flickered all the time. When I ran benchmarks keeping 100% load on the GPU in the background while browsing the web I don't get flickering. I bumped it up to 1.0v at idle and fixed the flickering problem. I had to Google search for this fix and it worked for me. Some say you need higher clock speed but I think it is just the default idle voltages set for these cards. I had to edit my Catalyst software as my 7950 is voltage locked. Hope this helps.

This is where I found my solution. It's old but still worked for me.

http://www.tomshardware.com/forum/281111-33-overdrive-underclocks

 

[MehraMilo]

You need to bump your idle minimum voltage to something a little higher. For instance my 7950 was at 0.950v idle and flickered all the time. When I ran benchmarks keeping 100% load on the GPU in the background while browsing the web I don't get flickering. I bumped it up to 1.0v at idle and fixed the flickering problem. I had to Google search for this fix and it worked for me. Some say you need higher clock speed but I think it is just the default idle voltages set for these cards. I had to edit my Catalyst software as my 7950 is voltage locked. Hope this helps.

This is where I found my solution. It's old but still worked for me.

http://www.tomshardware.com/forum/281111-33-overdrive-underclocks

Thanks for the reply, man. Unfortunately my 7950 is a 100352-3L, which I believe is voltage locked as well. GPU-Z seems to think it idles at 0.8V; not sure off the top of my head what the voltage is at load. I'll look into that thread--I'm a little hesitant to mess with anything related to voltage, but I'll give it a shot.

 

[ikuto]

Thanks for the reply, man. Unfortunately my 7950 is a 100352-3L, which I believe is voltage locked as well. GPU-Z seems to think it idles at 0.8V; not sure off the top of my head what the voltage is at load. I'll look into that thread--I'm a little hesitant to mess with anything related to voltage, but I'll give it a shot.

No problem because I was very annoyed by this problem too so I feel your pain. If you bump it up to idle at 1v there shouldn't be any harm since the voltages bumps up above that on full speed anyway which in my case goes up to 1.169v. You can try a lower voltage if it fixes it for you at 1v. Another thing I should mention is make sure you close all Catalyst related software before editing the profile file. I had to do it by using end task in the task manager to do this. Once you are done editing the file, just open Catalyst back up to take effect.

Good Luck!