Supremely pleased with Sapphire 7950 OC!

[Absolute0]

I think people like me get into watercooling mostly because it's a fun project. And it looks cool. The performance is great but not cost effective vs. a 50$ monster heatsink with a massive fan attached. But overclocking is a hobby, a hobby for enthusiasts, and for enthusiasts spending 400-600$ on graphics cards, "cost effective" becomes an increasingly relative term.

Any build that's truly "cost effective" precludes the 7970 and 7950 entirely.

Sorry I'm getting a bit off topic! hehe. I started out my overclocking career on XS where $$ is rarely a factor. It's more about pursuing your dreams, having fun building/modifying, and always pursuing higher clocks .

edit: i agree tho, I am pretty disappointed by the cost of GPU blocks these days. My EC7970 block was 120$!

 

[acefightr]

Great card this is. Go amd.

 

[DeeJayeS]

Been messing with my Sapphire 7950 OC edition at stock voltage (1.093). At the stock memory clock of 1250 the core clock will hit a stable 1075. However, if I increase the memory clock at all with core clock at 1075 I get instability...

Backing off the core clock to 1050 and 1062 I have run the memory clock up to 1625--haven't had time to go any further.

Maximum temperature is low 60s and fan profile in low 40s.

Anand's article mentions: "the memory clocks on all of our cards topped out at 5.8GHz [1450], beyond which we’d start seeing performance regressions from error correction on the memory bus." What does this mean and how can I tell when that's (or if it already is) happening with my memory overclocks?

Thanks.

 

[billbobaggins87]

Great card this is. Go amd.

ok yoda

 

[m3t4lh34d]

My 7970 is @ 1310/1700

on AIR I might add

 

[Tempered81]

nice go for 1350 / 1900

http://www.xtremesystems.org/forums...d-Torture-Your-Card-Post-It-Here!-quot/page17

 

[MrK6]

Been messing with my Sapphire 7950 OC edition at stock voltage (1.093). At the stock memory clock of 1250 the core clock will hit a stable 1075. However, if I increase the memory clock at all with core clock at 1075 I get instability...

Backing off the core clock to 1050 and 1062 I have run the memory clock up to 1625--haven't had time to go any further.

Maximum temperature is low 60s and fan profile in low 40s.

Sounds like you core was on the brink of stability at 1075, give it more volts or back down the clock, as you did. Nice going so far though :thumbsup:.

Anand's article mentions: "the memory clocks on all of our cards topped out at 5.8GHz [1450], beyond which we’d start seeing performance regressions from error correction on the memory bus." What does this mean and how can I tell when that's (or if it already is) happening with my memory overclocks?

Thanks.

Since the 5xxx series, AMD has implemented error correcting code (ECC) video memory. In respect to overclocking, the ECC can mask initial instabilities (artifacts, which we used to look for to know we'd overclocked our RAM too far) by running the data again. This manifests in a performance loss, which is now how we detect maximal overclocks. Simply, run a benchmark (3DMark11, built in game benchmarks, etc.) as you overclock your vRAM and check the score at the end. Eventually, you'll see performance regress as the increase in speed doesn't overcome the hit from ECC kicking in. Where this happens is specific for each card, but then you'll know that's your maximum overclock and should back off a bit.

 

[railven]

My 7970 is @ 1310/1700

on AIR I might add

Not sure if I've already asked you, but what model? And what are your temps and noise levels? Thanks

Since the 5xxx series, AMD has implemented error correcting code (ECC) video memory. In respect to overclocking, the ECC can mask initial instabilities (artifacts, which we used to look for to know we'd overclocked our RAM too far) by running the data again. This manifests in a performance loss, which is now how we detect maximal overclocks. Simply, run a benchmark (3DMark11, built in game benchmarks, etc.) as you overclock your vRAM and check the score at the end. Eventually, you'll see performance regress as the increase in speed doesn't overcome the hit from ECC kicking in. Where this happens is specific for each card, but then you'll know that's your maximum overclock and should back off a bit.

That's good to know. Since I don't really OC my GPUs much, I wasn't aware of this. Will be finally ordering next week unfortunately, none of the cards I keep eyeing are in stock haha.

Oh well, fingers crossed.

 

[DeeJayeS]

Since the 5xxx series, AMD has implemented error correcting code (ECC) video memory. In respect to overclocking, the ECC can mask initial instabilities (artifacts, which we used to look for to know we'd overclocked our RAM too far) by running the data again. This manifests in a performance loss, which is now how we detect maximal overclocks. Simply, run a benchmark (3DMark11, built in game benchmarks, etc.) as you overclock your vRAM and check the score at the end. Eventually, you'll see performance regress as the increase in speed doesn't overcome the hit from ECC kicking in. Where this happens is specific for each card, but then you'll know that's your maximum overclock and should back off a bit.

TY

 

[pieguy]

Well I was only able to get 950mhz core on my Sapphire 7950 OC on stock voltage, which has got to be the worst overclock on record thus far, lol. Ended up with 1050/6200 on 1.174v which I'm happy with although I was hoping for a little more. Of course I'm testing for stability with OCCT, which I don't think a lot of these overclocks that people are bragging about on the forums could stand up to.

 

[3DVagabond]

Well I was only able to get 950mhz core on my Sapphire 7950 OC on stock voltage, which has got to be the worst overclock on record thus far, lol. Ended up with 1050/6200 on 1.174v which I'm happy with although I was hoping for a little more. Of course I'm testing for stability with OCCT, which I don't think a lot of these overclocks that people are bragging about on the forums could stand up to.

~1.174 is stock voltage for a 7970. So, 1050 isn't too bad. Don't be afraid to up the volts a bit. 1.2 might let you open up more and shouldn't require you to crank the fans too much. People run a lot more, but it requires too much fan, IMO.

 

[pieguy]

~1.174 is stock voltage for a 7970. So, 1050 isn't too bad. Don't be afraid to up the volts a bit. 1.2 might let you open up more and shouldn't require you to crank the fans too much. People run a lot more, but it requires too much fan, IMO.

Yes 1.174 being stock for a 7970 is how I arrived at that number. I'm not very experienced at OCing video cards so what I don't understand is how people determine what is "safe" voltage for a GPU since there seems to be very little "official" information on the subject.

From the tests I did, I think my card may be stable at 1150 with ~1.225v but then again I don't know how safe that is. It gets close to 80c running OCCT at 65% fan speed but stays so much cooler running games, Heaven, etc. with a more reasonable fan setting.

 

[MrK6]

That's good to know. Since I don't really OC my GPUs much, I wasn't aware of this. Will be finally ordering next week unfortunately, none of the cards I keep eyeing are in stock haha.

TY

Glad to help. :thumbsup:

Well I was only able to get 950mhz core on my Sapphire 7950 OC on stock voltage, which has got to be the worst overclock on record thus far, lol. Ended up with 1050/6200 on 1.174v which I'm happy with although I was hoping for a little more. Of course I'm testing for stability with OCCT, which I don't think a lot of these overclocks that people are bragging about on the forums could stand up to.

Yes 1.174 being stock for a 7970 is how I arrived at that number. I'm not very experienced at OCing video cards so what I don't understand is how people determine what is "safe" voltage for a GPU since there seems to be very little "official" information on the subject.

From the tests I did, I think my card may be stable at 1150 with ~1.225v but then again I don't know how safe that is. It gets close to 80c running OCCT at 65% fan speed but stays so much cooler running games, Heaven, etc. with a more reasonable fan setting.

OCCT, like Furmark, is just a power virus, and I wouldn't count on it to reliably test your GPU. Really, all it does is test the efficiency of the cooling solution. Use strenuous gaming instead, as it'll load all components of the GPU evenly (instead of just maxing out the VRM's). Your clocks are going along well, and don't be afraid to push it to 1.225V as long as your temps stay low (and they're excellent so far). What are you VRM temp readings? Remember that the 7950 is the same chip and PCB as the 7970, just with parts disabled. Therefore, it'll have no problem running 7970 voltages and settings, and 7970's are fine up to 1.3V.

 

[superjim]

Here are my findings with the Sapphire 7950 OC:

Best clocks (so far): 1100/1500 @ 1.167v according to Afterburner, 1.157 according to GPU-Z, have seen this dip to 1.137v in GPU-Z while gaming/at load. 3DMark11 score is 8441 with main rig in signature. Temps while gaming have never been above 65C with auto fan speed. Have not ran OCCT/Furmark yet. 3DMark11, Batman AC and Crysis 2 are my stability testers.

At stock Sapphire voltage (0.993v) I could not get 950 bullet-proof stable. Upping this to "normal" 7950 stock voltage (1.090v) I was able to hit 1000 stable for 10+ hours of gaming.

As expected, upping core is a much bigger boost than upping memory. Have yet to see the ECC kick in at 1500 however from 1450 to 1500 (same core speed) I saw a measly ~40 point increase in 3DMark11.

 

[MrK6]

Here are my findings with the Sapphire 7950 OC:

Best clocks (so far): 1100/1500 @ 1.167v according to Afterburner, 1.157 according to GPU-Z, have seen this dip to 1.137v in GPU-Z while gaming/at load. 3DMark11 score is 8441 with main rig in signature. Temps while gaming have never been above 65C with auto fan speed. Have not ran OCCT/Furmark yet. 3DMark11, Batman AC and Crysis 2 are my stability testers.

At stock Sapphire voltage (0.993v) I could not get 950 bullet-proof stable. Upping this to "normal" 7950 stock voltage (1.090v) I was able to hit 1000 stable for 10+ hours of gaming.

As expected, upping core is a much bigger boost than upping memory. Have yet to see the ECC kick in at 1500 however from 1450 to 1500 (same core speed) I saw a measly ~40 point increase in 3DMark11.

Looking good so far. :thumbsup: Also, 3DMark11 wouldn't be very vRAM dependent since it's such a lower resolution. Play something like Crysis 2 @ 1080p+ and you'll see vRAM clocks have a much bigger impact (more so than previous generations).

 

[pieguy]

OCCT, like Furmark, is just a power virus, and I wouldn't count on it to reliably test your GPU. Really, all it does is test the efficiency of the cooling solution. Use strenuous gaming instead, as it'll load all components of the GPU evenly (instead of just maxing out the VRM's). Your clocks are going along well, and don't be afraid to push it to 1.225V as long as your temps stay low (and they're excellent so far). What are you VRM temp readings? Remember that the 7950 is the same chip and PCB as the 7970, just with parts disabled. Therefore, it'll have no problem running 7970 voltages and settings, and 7970's are fine up to 1.3V.

Hmm, interesting. I'm not sure what my VRM temps are, I don't see a way to monitor it in OCCT, Afterburner or GPU-Z. What's a good temp for VRM?

When we are talking about volts, should I just be paying attention to what GPU-Z shows for VDDC? Because I've just been going off of what I set it to in AB which I've read is not the way to monitor your voltage.

 

[pieguy]

I decided to try to find the OC "upper limits" of my card to help decide what to shoot for in a 24/7 OC. I went with 1200/1550 and set it to 1275mV in AB. Lower volts would cause Heaven to crash.

So looping Heaven for a while resulted in no problems, a max temp of 68 with 50% fan, and the VDDC fluctuating between ~1.21v and 1.25v. A few hours of BF3, Skyrim and CS:GO ran flawlessly with lower temps than Heaven.