7970 crossfire overclocking limits (help?)

[oldmanbal]

Hello fellow [H] Nuts,
I've been playing around with my 7970 oc Windforce gigabyte cards and have been trying to see what the wall was for overclocking. The cards clock higher as a single GPU but tend to have limits as far as the core will go in crossfire mode. I always want to squeeze as much honey out of a setup as humanly possible and every mhz yields improvement at 2560x1600 which is purely gpu limited in all scenarios during gaming. I would like to hear feedback from other 7970 owners to see what people are hitting for oc speeds in crossfire.

This is my current stable max:
1.2vcore
1225mhz core
1650mhz memory

Now the memory is maxed as far as the slider will go without enabling more headroom in MSI Afterburner. I would imagine there is some more headroom for memory but i don't know if it would yield any higher performance above 1650mhz. This is fast for memory, We are talking 6.6ghz which would be unfathomable a few years back.

My real issue is the core. I have seen these cards over 1300mhz with little adjustment to the vcore.

When I had a 5970 I was able to go from 725mhz up to 1ghz on the core, which is almost 30% overclock on 2 GPUs EACH! the performance increase at that level was absolutely mind boggling over stock. I was hoping for something to this effect so i bought the cooler running windforce 3x edition from gigabyte. I've had tremendous performance success with gigabyte products, including when i used to run the UD3p with an e8600 at 5ghz matched up with my 5970 and a 5870 for trifire.

What are other owners of cf 7970 getting for max core? Are there any tricks you are using to get a higher duel overclock stable on the core. Power is not an issue with my setup as i'm running a 950w psu that has never had a hiccup with any of the 3 different gpu configurations i've run through it (tri fire 5970+5870, and cf 6950 2gb @ 950core).

voltage seems to have absolutely no impact on the upper limit of the core as i get no difference in stability from stock voltage all the way up to 1.3 on the vcore. If over 1.3 would yield a benefit i have no problem unlocking the sliders to get a higher limit for the vcore. even at 1.2vcore, 1125mhz, and 1650mhz i have never seen the temps go over 65*c at automatic fan. Once i set it manually to 30% fan and my temps maxed out at 100*c without crashing (lets just say hot as shit.) I'll not do that again. Automatic on this setup is absolutely beautiful as these cards run unbelievably cool. Even at the factory oc of 1000mhz on the core I have NEVER seen it go above 60*c with automatic fan. This is why I bought this card in the first place.

Back to business. What manufacturor are you running and what do you have your max stable core/memory at? Let me know, and anyone that has suggestions for me to raise my limit, I'm 100% willing to try out anything you recommend. I'll be your g-pig. Tell me what to do.

Just to let you know, there is between a 12-20% increase in all my benchmarks going from 1000/1375 to 1125/1650 on the two cards.

BALLS DEEP BABY

 

[magoo]

RacerX registry hack.

 

[oldmanbal]

what are your numbers?

How do you like the 2410 in eyefinity? I opted for a single large 30" 2560x1600 ips monitor over eyefinity. I might pick up 2 more of them if i could even get a playable framerate at that absurd resolution.

 

[TroyX]

i never bothered to oc memory, you really dont gain much, and you can easily damage the card.

i would leave the memory alone, its high as it is.

i would leave the fan on auto at that clock speed on the gpu core and would not go over 1125mhz.

 

[magoo]

I have my 7970s at stock voltage......1.17V or something like that.

GPU is running 1175 and the memory is 1425. I have not gone higher because there is no need.

I watercool mine......no fan noise.

There is not a single game out right now that I can't run at least 60 fps in three screen Eyefinity.
I use 2410s in landscape.

You simply will not want anything else once you use Eyefinity or nvidia Surround. Honestly, I prefer Eyefinity. There is just way more game to see when you run three screens.

 

[oldmanbal]

i hit the wall just over 1125 in cf on the core.

 

[jaredpace]

overvolt the memory and clock it higher, 100% fan / open case bench, space the cards further apart, capacitor mod. Check your vrm temps. What type of PSU is it, and does it have caps in the PCIe leads? If your boards are reference you can flash the asus testbios and gputweak to 1.4/1.7. Picture of the rig, and screenshot of testing please.

Serious overvolting is making the cards attempt to pull more through the pci-e slots which are rated at 75watts.. its probably pulling 160watts off your motherboard and peaking at 200 while filling all the power rated through your pci-e power connectors. You need a high-end motherboard with good power circuitry - some mobos let you alter pcie power variables. /xcl /rcl -xcl with afterburner, or a new bios will let your raise your memory oc limit.

Test each card by itself in the rig and go for maximum core speed with default mem and 1650 mem and max mem. record your numbers for each card, attempt the oc with 100% fan and max volts, I bet each card by itself will do near 1300 or more. Together at 1225 is not bad, it's still one of the highest CF air overclocks you'll see.

Would like to know model of the mobo and psu

 

[qiplayer]

Hello fellow [H] Nuts,
I've been playing around with my 7970 oc Windforce gigabyte cards and have been trying to see what the wall was for overclocking. The cards clock higher as a single GPU but tend to have limits as far as the core will go in crossfire mode. I always want to squeeze as much honey out of a setup as humanly possible and every mhz yields improvement at 2560x1600 which is purely gpu limited in all scenarios during gaming. I would like to hear feedback from other 7970 owners to see what people are hitting for oc speeds in crossfire.

This is my current stable max:
1.2vcore
1225mhz core
1650mhz memory

Now the memory is maxed as far as the slider will go without enabling more headroom in MSI Afterburner. I would imagine there is some more headroom for memory but i don't know if it would yield any higher performance above 1650mhz. This is fast for memory, We are talking 6.6ghz which would be unfathomable a few years back.

My real issue is the core. I have seen these cards over 1300mhz with little adjustment to the vcore.

When I had a 5970 I was able to go from 725mhz up to 1ghz on the core, which is almost 30% overclock on 2 GPUs EACH! the performance increase at that level was absolutely mind boggling over stock. I was hoping for something to this effect so i bought the cooler running windforce 3x edition from gigabyte. I've had tremendous performance success with gigabyte products, including when i used to run the UD3p with an e8600 at 5ghz matched up with my 5970 and a 5870 for trifire.

What are other owners of cf 7970 getting for max core? Are there any tricks you are using to get a higher duel overclock stable on the core. Power is not an issue with my setup as i'm running a 950w psu that has never had a hiccup with any of the 3 different gpu configurations i've run through it (tri fire 5970+5870, and cf 6950 2gb @ 950core).

voltage seems to have absolutely no impact on the upper limit of the core as i get no difference in stability from stock voltage all the way up to 1.3 on the vcore. If over 1.3 would yield a benefit i have no problem unlocking the sliders to get a higher limit for the vcore. even at 1.2vcore, 1125mhz, and 1650mhz i have never seen the temps go over 65*c at automatic fan. Once i set it manually to 30% fan and my temps maxed out at 100*c without crashing (lets just say hot as shit.) I'll not do that again. Automatic on this setup is absolutely beautiful as these cards run unbelievably cool. Even at the factory oc of 1000mhz on the core I have NEVER seen it go above 60*c with automatic fan. This is why I bought this card in the first place.

Back to business. What manufacturor are you running and what do you have your max stable core/memory at? Let me know, and anyone that has suggestions for me to raise my limit, I'm 100% willing to try out anything you recommend. I'll be your g-pig. Tell me what to do.

Just to let you know, there is between a 12-20% increase in all my benchmarks going from 1000/1375 to 1125/1650 on the two cards.

BALLS DEEP BABY

Hello!! I'm happy to read of you that have 2 windforce in crossfire.

I was wondering how was the rest of the system with the temps, As I'm planning to buy 2 windforce and got a double 140 rad on top of the mobo for cpu watercooling, and the hot air from the cards would in part go through it.

But coming to your issue, I've calculated, seeing on a review where they overclocked the card to 1300mhz, that the 2 card need more than a 1000power supply.
One card + system used 570 watts, the system was 160.
One card itself used 410 watts at 1300 mhz.

So...
160 the system
820 the 2 OC cards
50 the fans, controllers, lights and so on....
A total of 1030 watts

it needs alot of power, I think that your problem is the 900 watt powersupply.



Coming to my perplexity about heat, wha'ts your case tipe? Do you have a rad somewhere? Do you have high temps inside it? What's your opinion about it?

I have the NZXT phantom
the inside looks like

as you can see on top there is the 280mm rad



I hope that the 210 side fan that I can put here:

would be enough to take out the hot air of the cards