VisionTek 7970 Poor OC Results

[Eureka]

Well, still looking for solutions.

I've overclocked just the core, and the best I've managed is about 1150 on 1.38V. At 1.3V, I'm close to stable at 1125 mhz but not much better. Also I realized I never upped the power % in Trixx, but it's at 20% now. Maybe this is just the upper limit?

However, I found in another thread that flashing the bios may give better results. Can anyone chime in on this?

 

[MrK6]

A stock voltage of 1.175V is probably the biggest indicator that your chip will have difficulties clocking up. However there's more you can do with the chip than just throw volts at it. First, don't put anything above 1.3V through a chip on air, and I'd even limit it to 1.25V for 24/7 as you're looking at noticeable degradation otherwise. Obviously volts don't work, so you have to return to the bag of tricks to try something else - in this case, cold is going to be your best bet.

Cooling in general reduces the resistance of the chip and allows you to reach higher speeds at the same voltages. Specifically in the case of high-leakage chips, which I suspect you have, you'll get a much better response the lower you go. First, try cranking the fan to 100% and seeing how far you get on stock voltage. Re-applying the TIM with something better could also be worth it. You can also try getting some better cooling by going water (custom loop or slapping an all-in-one on the board with some zipties), but probably isn't worth the money. I imagine this chip truly wouldn't shine until you at least got it under chilled water, and even then it still might be a dud.

In the end, let up the volts, keep it cool, and don't touch the RAM until you figure out the core's maximum.

 

[RussianSensation]

I've overclocked just the core, and the best I've managed is about 1150 on 1.38V.

Ok do this simple test. Download MSI Afterburner (go for 2.2.1 version I linked below).

1100mhz at stock voltage in Unigine Heaven 3.0 at 8xMSAA / Extreme Tessellation. Fix GPU fan speed to 85%. Record maximum GPU temperature.
1100mhz at "1.38V in Sapphire Trixx" with same settings. Fix GPU fan speed to 85%. Record maximum GPU temperature.

Report back GPU temperatures back to us. I bet your voltage control is not working.

So I picked up one of the VT 7970 GHz from the deal last week... looks like I'm OCing pretty poorly?

I can't seem to get it to stabilize past 1100 Mhz at any voltage. Stock is 1.175V. At 1100 MHz, around 1.225-1.250 will get it to run Heaven without any noticeable artifacts. At 1150 MHz, nothing will run artifact-free; I maxed out Trixx with 1.381V and it still artifacts noticeably. My GPU-z ASIC quality is 66.8%. Am I doing something wrong or did I just lose the silicon lottery massively?

I am going to asking the obvious -- How do you know your voltage is even working?

For example, you can move the slider in Sapphire Trixx but unless you have enabled MSI Afterburner voltage unlock, it doesn't mean the voltage is unlocked. Out of the box, almost all HD7970 are locked in software without doing an unofficial MSI voltage unlock. You can still move the GPU voltage slider in Sapphire Trixx, and press Apply, but it won't do anything to hardware voltage in reality.

Did you actually check that your GPU voltage rises in GPU-Z (Sensor --> VDDC) under load or double checked that reading in HWInfo64? The fact that your GPU won't go above 1100mhz at any voltage is an indication to me your voltage is most likely locked.

Your ASIC is not low enough to not get 1100mhz. I've tested 3 7970s with ASICs of 59-63% and all of them hit 1150mhz with a slight voltage bump and 1200mhz at 1.25V. My guess is your voltage control is not enabled and your stock voltage of 1.175V in MSI AB/Sapphire Trixx (your target voltage only) is undervolting on top of this. In other words your actual Vdroop voltage with 1.175V is probably only 1.125-1.15V or even lower. My recommendation is to do an Unofficial MSI Afterburner voltage unlock (you'll need MSI AB 2.2.1 or earlier or need to import 2 .dll files into the MSI AB folder otherwise).

Under the heading [ATIADLHAL], add these 2 lines:
UnofficialOverclockingMode = 1
UnofficialOverclockingEULA = I confirm that I am aware of unofficial overclocking limitations and fully understand that MSI will not provide me any support on it

Adjust the voltage in MSI Afterburner, not Sapphire Trixx. Also, you may need to download Asus GPU Tweak to enable range enhancement for GPU clocks beyond 1125mhz. Your GPU would probably be hitting 90-100*C at 1.381V on air, not to mention this type of voltage is very dangerous to apply on air in the first place. Once you get MSI Unofficial voltage control working, go very very slow. Don't do anything like you just did with Sapphire Trixx, unless you want to kill your GPU.

 

[Eureka]

Sorry about this, I completely forgot about this thread. RussianSensation, very helpful information! I found out that it wasn't actually upping the voltage, and I used the MSI method. Now I'm verifying in GPU-Z that the voltage is jumping past 1.2V.

Now something stranger is happening. I put a mild overclock (1100mhz, 1.21V, 120% power). Now, everything is artifacting (including windows). Screen will tear if I change between windows. If I revert back to stock, Heaven will crawl at 11 fps with 100% GPU usage. If I just put down the overclock and restart the computer, everything is fine again. What's going on here?

EDIT: for some reason any overclock is unstable in MSI afterburner. I just reset everything, restarted the computer, and it overclocks fine with Trixx to 1100 mhz. If I do stock voltage and 1100mhz in afterburner I get horrible screen tearing.

EDIT2: So I figured out why it's tearing... I have to reset the unofficial overclocking to 0 before it can overclock stably. Now it has the voltage slider, but voltage peaks at 1.18V. Damn.

EDIT3: Nevermind, I can still control voltage... it doesn't really seem to peak any higher than 1.18 unless I go above 1.25V. I took it up to 1.275V slowly, with 100% fan. Temps were comfortable but it was still artifacting at 1175mhz @ 1.275V (only ran for a few minutes with 100% fan).