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Help overclocking reference 7970

kissenger

kissenger

kissenger

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Joined
10 Apr 2008
Posts
2,491
So I've just installed a reference 7970 (MSI OC edition) and I want to make sure I get the most out of it so I just want to run this check list by you lot. This is the plan.

1. Bump core clock by 15MHz.
2. Do a couple loops of Unigine Heaven.
3. No artifacts, repeat step 1. When I start getting artifacts or crashes, bump voltage by 5mV.
4. When I've reached my max core overclock either because of temps or because I've reached 1.3v, start bumping memory in 15MHz increments until I start getting artifacts or crashes.

Sound about right?
 
I read that you can get a better OC by doing it in small increments though. Is that wrong then?

BTW, just did a quick Heaven bench and this was the result. Not bad, especially the minimums. This is at 1010/1375 btw:

7970_stock.png
 
So I think I got a pretty good chip. I've managed to push it to 1100/1525 so far in Heaven at stock voltages and I'm not getting any problems. I'll try to push it to 1200/1600 tomorrow.

The main thing with this card seems to be keeping the temps down. The fan is noisey, but if you can live with it, it does keep the card cool.

Edit: couple of questions:

Is there 'good OC' I should aim for? I.e. what are people maxing out at with this GPU? From what I've seen it's around 1250/1750.

I noticed that the limits in AB are 1175/1575. How do I unlock this limit?
 
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My ASIC quality according to GPU-Z is 73%. Is that any good?

So far I am super impressed by this card. 1175/1575 at stock volts. Temps staying below 70C (albeit with a fairly aggressive fan profile).
 
If I'm not messing with the memory voltage do I need to worry about VRM temperatures?

The memory on my card seems to have a lot of headroom. Don't want to push it too far though. Got this rock solid stable at 1162/1700.
 
So I think I hit a bit of a wall with this chip.

Having tested more, my best at stock is 1125 core. A little bump upto 1181mV gets me to 1150 core. However, I can't seem to get upto 1170 core no matter what I do. I've been all the way up to 1250mV in increments and no luck.

I know voltage control is working because temperatures do increase if I bump the voltage in Afterburner. I'm also keeping temps very low. 65C is the highest it's been and returning the memory to stock doesn't help either.

Have I just ran up against the limits of the chip?
 
Thanks for the advice.

So my best bet is to try 1.3v and 1170 on the core, and if I can get through heaven then start reducing voltage until I get problems?
 
Okay I've configured AB to show VRM temps and just did another pass of Heaven at the following:

1237mV
1170 core
1375 memory
Power limiter at +20

The first pass I got through mostly unscathed. Few slight artifacts at the draon statue, but on the second pass they became worse, so I suppose that means I'll need more volts.

Btw, VRM temps never passed 75C and core temps never passes 65C.

Also on a related topic, I was playing BF3 last night and everything was mostly fine, but at one point I noticed a big drop in frame rates and looked at my AB settings and the card had downclocked itself to stock settings. Is that something to worry about? Never had it happen before on any card.
 
I just did a Heaven run with fans at constant 80%. VRMs got upt to 74C, core got up to 64C. Memory voltage in AB is 1600mV.

At 1250mV/1170 I got through the benchmark pretty much unscathed. Saw like 1 or 2 mild texture flickers the whole way through.
 
Well I think my core maxed out at 1170 because nothing up to 1.3v can get it stable at 1180. Heaven is stable at 1170/1600, 1125mV. Temps at 65/75C. I think I could probably get a stable overclock at 1170/1675, which is pretty decent imo. Might also be able to get core voltage down a bit. I'll have a go later when I've got a bit more time.
 
I'm still looking into ways of seeing if I could increase this overclock safely. One weird thing I did notice just now as I was messing about with some stuff is that if I open up AB and load my max OC profile (which is at 1.2V) and open GPU-z at the same time, GPU-z shows that my card is only drawing around 1.14V even at 100% load.

Is that just a bit of weirdness to do with GPU-z or is there something going wrong here? The strange thing is that the voltage readings for the memory and all other setting correlate perfectly in GPU-z and AB.

It does seem a bit weird to me that I can get a fairly high OC on stock, but then virtually nothing after that no matter what I do to the volts. Maybe AB isn't upping the volts as it should and that's why I'm getting instability at pretty much anything above my max stock OC?
 
Hmm... this is very strange. I tried Trixx and I got the same result, except this time I used HWINFO64 to monitor voltages and it also shows that the voltage isn't going above 1.174v even at 100% load. This is the case even if I bump voltage to 1.3v in Trixx. I downloaded HIS Turbo but there's no option to change voltage control.

If voltage isn't changing I'm kind of pleased, because if I can fix the problem I should be able to get a better OC :D

Don't know why I can't adjust voltage though.
 
Thanks Tommy! You're very helpful :D

I'll try that out probably tomorrow. I should be able to tell one way or the other what is going on then. If I can get above 1160 core on the GHz BIOS then something must be wrong with Afterburner.
 
tommybhoy said:
No problem, makes a change from us shouting at each other last year, looking back, when I read it again, it's soo funny how two guys can get so heated!:D
Click to expand...

Hahah! And over the issue of vram! Not our finest hour :D

And yeah, pretty sure I followed it to the tee, but the thing is I have done a Windows reinstall for a year and I've had several GPUs in my system in that time (incl. another 7970 which was volt locked) and countless installs and reinstalls of programs like AB, Trixx, GPU-z, etc, etc, so there could easily be a conflict there somewhere.

Btw Tommy, does your GPU-z register the exact same voltage as what AB shows when you're running an overclock? I'm wondering if it might be just a general inaccuracy issue to do with GPU-z.
 
Regarding flashing to the GHz bios, can I not just use ATIWinflash? It looks so simple and the DOS flashing method you linked to, Tommy, looks so complex :eek:
 
Actually that looks fairly easy. Thanks. I think I'll try that. I've already saved a copy of my old bios with GPU-z though so can I skip that step?
 
Greebo said:
Well flashed with the GHz bios, clocks read right for that bios. Only issues are that it's not locked at 1.25v (its actually 1.218v) so I can still change voltages.

% loading is locked at +20% though which is disppaointing.

My overclocking on this bios is worse than my original one so switch back to it for now,.
Click to expand...

I'm going to flash mine tonight. I've heard mixed accounts of whether or not the GHz bios gives a better overclock, but I suppose it's worth a shot.

What 7970 do you have, Greebo? MSI OC reference?
 
Okay, just flashed. Everything seems fine. Only slight hiccup was I got an 0FL01 error the first time I tried to flash, but I just added -f to the command line and then it flashed fine.

Booted up and opened AB and my new clocks are 1050/1500. However, the voltage is at 1131mV by default, not 1250mV.

Edit: did a bit more testing and I'm still getting some weirdness with this voltage. I don't think my voltage control is working tbh. Like I say, new default in AB is 1131mV. However, HWI shows my voltage under load to be 1256mV, but GPU-z shows voltage to be a max of 1176mV under load!

The reason why I think my voltage control isn't working is because, even with this new BIOS, my overclock ability stays the same. I can pass Heaven easily at 1150/1600, but I can't pass at 1170/1600 no matter what I do to the voltage.

For now I'm just gonna play some games and forget about overclocking this card, but if anyone has any advice as to what I can do, I'd appreciate it. I think the next thing I'll try is a reinstall of Win7.
 
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You're probably right, Tommy, but I can't not get the voltage unlocked on this thing after having already returned one 7970 because of a hardware voltage lock :(
 
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