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7970 CFX Refusing to overclock

S

Smarshallsay

n00b
Joined
Feb 7, 2007
Messages
7
I have two VTX3D 7970 cards in my machine. They are at the stock clocks 925 / 1375 @ 1174mv.

I have tried to overclock but the highest I could get the core is 1055 before I got errors immediately in OCCT (or the PC just hangs).

Increasing the core voltage doesn't seem to make any difference, in fact if anything it made it worse. I tried the voltage at 1.300 (not intended for 24/7 use, I just wanted to know the limits of my cards) and OCCT crashed even with the cores at 958.

My GPU memory on the other hand seems to work fine, it reaches the max allowed in afterburner (1575) with seemingly no problems.

- Is it harder to overclock these because I am running crossfire?
- Should I have overdrive set to 0% power limit when increasing the voltage manually?
- My 2600k is overclocked to 4.8Ghz (Asrock Extreme7 Gen3) are there any BIOS settings that might be affecting my graphics card OC?


Please advise!
 
I have a 2600k at 4.8 ghz, 3 Gigabyte reference 7970s all at 1100/1500 on stock voltages and still 0% in overdrive. I can push more but these are my everyday never crashed settings. Sounds like your cores ( or one of them ) are just tapped out.
 
Crossfire is funny when trying to OC any AMD cards, especially the 7970s.

I use +20% in Overdrive, and my GPUs are set as far to the right as CCC will allow......1150 I guess.
Memory is currently running at 1400.
My cards are rock solid at those settings.

I like to use Afterburner to monitor my cards useage, but it will not unfortunately OC a Crossfire setup.
I have not given Trixx a try, essentially because it has no monitoring functions, but you might want to give that software a try.
 
Try overclocking them with crossfire disabled see if your cards are faulty or maybe your psu doesn't have enough amps or watts
 
Smarshallsay said:
I have two VTX3D 7970 cards in my machine. They are at the stock clocks 925 / 1375 @ 1174mv.

I have tried to overclock but the highest I could get the core is 1055 before I got errors immediately in OCCT (or the PC just hangs).

Increasing the core voltage doesn't seem to make any difference, in fact if anything it made it worse. I tried the voltage at 1.300 (not intended for 24/7 use, I just wanted to know the limits of my cards) and OCCT crashed even with the cores at 958.

My GPU memory on the other hand seems to work fine, it reaches the max allowed in afterburner (1575) with seemingly no problems.

- Is it harder to overclock these because I am running crossfire?
- Should I have overdrive set to 0% power limit when increasing the voltage manually?
- My 2600k is overclocked to 4.8Ghz (Asrock Extreme7 Gen3) are there any BIOS settings that might be affecting my graphics card OC?


Please advise!
Click to expand...

Bro,

I had some problems OC'ing crossfire as well, and it took me a couple of hours to get it sorted. First, did you extend your clocks? Here's what I suggest:

1) Install ASUS GPU TWEAK to extend clock range and only extend clocks (install, click advanced, then tuning | enable "extend overclock range"
2) uninstall asus gpu tweak
3) once clocks are extended, use msi afterburner (latest beta 2.2.15)
4) be sure to select "synchronize graphics cards"
5) don't bother upping the voltage yet - unless you have a high ASIC
6) try to get your max stock overclock with sync'ed 7970s. This setting basiaclly syncs the voltages between your 2 cards - i found instability if I didn't enable it.

If you try to use different voltages between the cards you will lock up. I think this may help you greatly, this is what clinched my overclock on xfire 7970s.
 
I've never had much luck overclocking my GPU's in Crossfire or SLI. Even when both cards OC well independently they just don't maintain stability very well when together. The PSU could be the culprit though. In my case I've only ever had two different PSU's since I started SLI/CFX'ing and I've never really had an alternate PSU to test with.

Are there any motherboard specific voltages which would aid in multi-GPU overclocking (PCIe voltage perhaps)? I haven't really looked into it that much.
 
Last edited:
i have the 5970, and here is my little problem...

If the card is hooked up to a single monitor then i dont have a problem. If i have the HDMI cable hooked up to my reciever just for 5.1 sound and NOT for another monitor then it will allow me to overclock HOWEVER the card stutters alot in 2d mode. 3d is ok but it is irritating. My little fix around was that in idle the core clocks itself to 157 and 300( core/memory) and by adding a profile which foced the clock speeds in idle to 400 core and 1000 memory it solved everything. I know the cards are vastly diff and 2 cores on a single chip, maybe u should see if u have multiple monitors or using the HDMI for sound. The card appears to have a driver problem that to this day wasnt solved. If i didnt know ALOT about voltage regulators and other asspects on video cards i would swear it was a broken card. By the way, with my moddified clocks the card plays flawlessly and has done so for the past 2.5 years. Give it a try, ya got nothing to lose. If ur problem remains erase the profile and no damage at all will happen to ur card nor will it void the warrenty. Best of luck.
 
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