Help on overclocking a Sapphire 7970 OC w/boost

[ruhtraeel]

Hey,
I'm trying to overclock my GPU right now, as I would like my FPS to be over 40 at all times in Crysis 3.

I've already bumped up the clock speed to 1ghz, up from 950mhz.
When I open the Sapphire TriXX software, the VDDC shows a default value of 1050.

This seems low for a 7970, I was hoping that I could get 1100mhz without touching voltage, but when I try to bump up the clock speed, Crysis 3 ends up crashing the driver or the game itself.

Am I doing something wrong? When I try to bump up the mV in MSI Afterburner (it has a default value of 1025) and then bump up the clock speed, I get artifacts coming out of characters while in-game.



EDIT: I also think it's worth noting that if I switch to the alternate BIOS on the 7970, the entire screen artifacts on the desktop after a while.

Thanks

 

[powruser]

I believe that VDDC is separate from the GPU voltage. I think VDDC is the memory voltage or something. Go into the settings of the overclocking utility you're using at see if there's a setting that will show the GPU's core voltage.

 

[Sohaltang]

One of the bios on that card is voltage locked. Try switching to the other and try again

 

[tg2708]

One of the bios on that card is voltage locked. Try switching to the other and try again

How can this bios switch be done? I'm having similar issues as op.

 

[Ieat]

If the game crashes or you see artifacts the overclock(core and/or memory) is not stable. Raise voltage or lower clock speeds.

 

[Sohaltang]

How can this bios switch be done? I'm having similar issues as op.

There is the tiniest of switches on the top of the card near where you screw it down. Power off and flip the switch. If I remember correctly one is a GHZ clock and the other is slower. Cant remember which one I had to use to get it to OC.

 

[tg2708]

There is the tiniest of switches on the top of the card near where you screw it down. Power off and flip the switch. If I remember correctly one is a GHZ clock and the other is slower. Cant remember which one I had to use to get it to OC.

Flipped the switch to 2, but I may sound a bit foolish here but shouldn't the core clock change from 950 to 1000mhz (say so on the box, 1000 with boost)?

 

[monkeydelmagico]

I see you are using afterburner. Try using trixx first. Make sure you have set up trixx to allow for voltage control.

 

[Sohaltang]

Flipped the switch to 2, but I may sound a bit foolish here but shouldn't the core clock change from 950 to 1000mhz (say so on the box, 1000 with boost)?

It should. Make sure you restart windows. I know in windows 8 changes did not take effect just doing a shutdown since it is not a true shutdown.

 

[ruhtraeel]

So I switched to the alternate BIOS, changed VDDC in Trixx from 1050 to 1100, and changed my clock speed from 1000 mhz to 1100 mhz. Did a quick test of Crysis 3 (less than 5 minutes); there's no artifacting, and it doesn't crash within 5 seconds of playing.

Things seem to be going well, I might have to stress test it, but 1100 VDDC seems reasonable, right?

HWMonitor says that the max VDDC my 7970 is taking is 1.20.


EDIT: Restarted my computer, Trixx defaulted VDDC back to 1050. Now after I bumped it up to 1100, it still artifacts.

EDIT2: It seems like just when I boot my machine up and apply the new voltages, nothing artifacts. I tried slowly bumping the voltage down, and I got the VDDC to around 1075 before Crysis 3 crashed. However, upon raising it back to 1100mhz, it still continued to have artifacts unlike when I boot it up at the very beginning.

I think 1100mhz is the bare minimum for voltage where I can run 1100mhz stably.