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Problems OC'ing My 7970

#1BeefCastlePosted 9/2/2013 1:13:15 AM
I decided to overclock my 7970 today. I was inching up my core and memory clocks and running furmark after each one testing for stability. I'm pretty sure I got a dud of a card when it comes to overclocking, wasn't able to get my core over 1120 without some minor artifacting. But that's not the problem. After settling on my modest overclock I was surfing the web and a flash video popped up and my screen immediately when into a weird glitchfest of mostly blue screen with some random lines in it. After some trial and error I figured out that if I bring my memory clock to anything over stock, even 1430 which is 5 over, it will do this every time on flash videos. When I lower it back to 1425, all is well. I even played some Witcher 2 with the memory clock OC'ed and had no problems. Only seems too effect videos. I don't get it, anyone got any ideas whats going on?
#2DeanWhipperPosted 9/2/2013 1:56:02 AM
Sounds like a driver issue
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Is this even legal? http://www.youtube.com/watch?v=3Fxhiq93TTg
#3DarkZV2BetaPosted 9/2/2013 4:11:50 AM(edited)
That's pretty normal, actually. Pretty sure AMD holds back poorly binned chips from early batches to keep reception favorable, both with CPUs and GPUs.
It happened in the past with the HD6 series as well, and seems to generally be a trend. Wouldn't surprise me if nVidia and Intel do this as well.
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Want that Shield!
Ball and Cup on ps mobile has framerate issues. -stargazer64
#4ShebeskiiPosted 9/2/2013 6:26:52 AM(edited)
I think this sort of binning is very normal.

I'd like to see evidence that 7950s and 7970s still OC well, on average.

No doubt older ones do, but I doubt it now.

My within 1-2 month release 570 had an ASIC of 86% and could OC to almost 900 core (up from 732) on the stock cooler and still be far from max safe voltage. I just needed a better cooler to be ridiculous about it.

It died because I OC'd the memory like crazy awhile back, which ruins the life of that card (and most cards), but it still lasted 2 years for myself and I did that stupidity (which caused horrible memory artifacting) when I first bought it.

The replacement is still 82% ASIC, but I'm not going to bother pushing this one. I don't know if Nvidia does this too. More than likely. Hard to say if it's as aggressive. OC headroom on Nvidia cards is pretty modest anyway this gen.
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That which can be asserted without evidence, can be dismissed without evidence. - Christopher Hitchens
#5BeefCastle(Topic Creator)Posted 9/2/2013 8:49:54 AM
Hmm drivers really? I guess i can roll back and see if it helps.
#6Snuckie7Posted 9/2/2013 9:04:05 AM
I don't think it's the drivers. The core is probably stuck where it is without more voltage due to what DarkZV2Beta described, and the memory probably uses Elpida IC's which don't overclock very well. The 7970 has a lot of bandwidth already, so the memory isn't going to make much of a difference. For the core, you just need more voltage.
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Intel Core i7 3820 | EVGA X79 SLI K2 | MSI 7950 Twin Frozr III | Samsung / 840 120GB / 8GB RAM | 1TB WD Caviar Blue | Corsair / 550D / H70 | Silencer MKIII 600W
#7BeefCastle(Topic Creator)Posted 9/2/2013 9:20:20 AM
Well, I'm just using the CCC to do the OC'ing and i've upped the voltage with the power control setting slider in the graphics overdrive tab. The slider is weird, you can go from -20%power to +20%power. No actual voltage setting. Either way I upped it to +20%. The glitching in videos is still confusing me, why should a 5 MHz overclock on the mem cause a complete glitch out on videos but work fine in games.
#8Snuckie7Posted 9/2/2013 11:42:44 AM
You can't adjust the voltage in CCC at all. Use something like MSI Afterburner or Sapphire Trixx to overclock. It's no wonder why you couldn't push the core further; 1120MHz on stock volts is actually pretty good (if your card isn't locked at 1.25V). The memory probably still can't be pushed any more though.
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Intel Core i7 3820 | EVGA X79 SLI K2 | MSI 7950 Twin Frozr III | Samsung / 840 120GB / 8GB RAM | 1TB WD Caviar Blue | Corsair / 550D / H70 | Silencer MKIII 600W
#9BeefCastle(Topic Creator)Posted 9/2/2013 12:43:00 PM
Ahh, ok I thought the slider bar was weird. What does that do then? do I need CCC then, or can I just uninstall and use MSI?
#10DarkZV2BetaPosted 9/2/2013 1:04:59 PM
Power target is just that: the card will throttle to stay within that limit.
Isn't CCC how you control all driver level 3D settings? It's probably good to keep it around.
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Want that Shield!
Ball and Cup on ps mobile has framerate issues. -stargazer64