[th3illusiveman]

Hey guys,

What's the OC voltage sweetspot for a 7970 for 24/7 use? I was thinking 1250mv would be safe for 24/7 if temps allow, is this correct? Also what voltage is the redline (ex 1.3v?) that should not be used for more than afew minutes.

Thanks in advance

 

[twerk]

1.3V is the absolute maximum the card will allow without modding, most people run at 1.25V or less for a 24/7 OC. 1.3V is fine as long as your temps are under 70 degrees.

 

[th3illusiveman]

Quote:

Originally Posted by AndyM95

1.3V is the absolute maximum the card will allow without modding, most people run at 1.25V or less for a 24/7 OC. 1.3V is fine as long as your temps are under 70 degrees.

Thank you sir

Guess i'll see what this thing can do at 1.2 then slowly move up to 1.25.

hoping for ~1200Mhz+ as my final OC.

 

[glina]

You'll probably have no problem keeping the core temperatures in check, but take care of the VRM temps as well. They rise much faster than core temps when o/cing.

 

[th3illusiveman]

Quote:

Originally Posted by glina

You'll probably have no problem keeping the core temperatures in check, but take care of the VRM temps as well. They rise much faster than core temps when o/cing.

What's their limit? The highest i've seen so far is 71c

 

[raghu78]

Quote:

Originally Posted by th3illusiveman

What's their limit? The highest i've seen so far is 71c

you are safe. keep VRM temps below 90c and core temps below 70c. 1200 mhz is the sweet spot for tahiti. beyond that the power and heat/temps increase is disproportionate to perf increase.

 

[th3illusiveman]

Quote:

Originally Posted by raghu78

you are safe. keep VRM temps below 90c and core temps below 70c. 1200 mhz is the sweet spot for tahiti. beyond that the power and heat/temps increase is disproportionate to perf increase.

Something is wrong with my Heat sinks again.

ran 3dmark at 1.225mv and Vrm1 went up to 90c, Vrm2 was only 66c and the GPU was at 51c

 

[raghu78]

Quote:

Originally Posted by th3illusiveman

Something is wrong with my Heat sinks again.

ran 3dmark at 1.225mv and Vrm1 went up to 90c, Vrm2 was only 66c and the GPU was at 51c

http://www.xbitlabs.com/articles/coolers/display/arctic-accelero-xtreme-7970_5.html#sect1

its possible because the main body of the arctic xtreme 7970 cooler does not make contact with the VRM heatsinks. the cooling is only based on air blown by fans onto vrm heatsinks. what are your core clocks ? the fans on the arctic xtreme 7970 are very silent. push the fan speed to 70%. see if that makes an improvement in VRM temps.

 

[th3illusiveman]

Quote:

Originally Posted by raghu78

http://www.xbitlabs.com/articles/coolers/display/arctic-accelero-xtreme-7970_5.html#sect1

its possible because the main body of the arctic xtreme 7970 cooler does not make contact with the VRM heatsinks. the cooling is only based on air blown by fans onto vrm heatsinks. what are your core clocks ? the fans on the arctic xtreme 7970 are very silent. push the fan speed to 70%. see if that makes an improvement in VRM temps.

i was thinking about doing this.

On the default 7970 cooler there is a black heat spreader that goes over the VRMs, the memory chips and afew capacitors. What if i put that thing back onto the PCB then put the white heatsinks that came with the accelero onto the that.

So it would be PCB VRMs>Stock Thermal Pad> Stock Heat spreader>Accelero Heatsinks> Air from the fans.

pics

 

[raghu78]

i don't think it will work. you could try the stock heat spreader instead of the vrm heatsinks. it should work. the stock heatspreader is quite effective. as i said try and get some very good thermal pads like fujipoly extreme. the air blown by the xtreme 7970 combined with quality thermal pads and stock heatspreader should cool memory and vrm effectively.

 

[glina]

Quote:

Originally Posted by th3illusiveman

On the default 7970 cooler there is a black heat spreader that goes over the VRMs, the memory chips and afew capacitors. What if i put that thing back onto the PCB then put the white heatsinks that came with the accelero onto the that.

So it would be PCB VRMs>Stock Thermal Pad> Stock Heat spreader>Accelero Heatsinks> Air from the fans.

I think that would work, if theres enough clearance between the Accelero and the PCB.
Otherwise the stock heatspreader will do a better job at keeping the VRM's cool. The side effect is that it heats up your memory chips with the VRM-generated heat, which could mean a lower memory-oc comparing to a separate heatsink solution.

 

[martinhal]

Are the vrm temps in gpuz accurate ?

 

[th3illusiveman]

Quote:

Originally Posted by martinhal

Are the vrm temps in gpuz accurate ?

yes, i checked with Hwinfo64 to compare. The only issue is they read VRM1 and VRM2 opposite to each other.

(Ex GPU-z [Vrm1-60c/ Vrm2-80c] Hwinfo64 [Vrm1-80c/ Vrm2-60c] )

 

[glina]

Quote:

Originally Posted by martinhal

Are the vrm temps in gpuz accurate ?

Measured mine with a laser gun and they match down to 1C with the GPU-Z readout. This is on 7950 Vapor-X.

 

[RaleighStClair]

So i guess my VRM readings aren't accurate as they read 25C @ 1220/1640 on my 7970?

 

[th3illusiveman]

Quote:

Originally Posted by RaleighStClair

So i guess my VRM readings aren't accurate as they read 25C @ 1220/1640 on my 7970?

That's a great temp.

Use both Hwinfo64 and GPUz and to confirm

 

[th3illusiveman]

Gah! this VRM1 temp is really holding this GPU back! Just 3DM11 benched 1275Mhz/1500Mhz with 1218mv and completed a full Ungine Heaven 4.0 run with it

I know i could at least bench 3DMark at 1300Mhz if i could turn the juice up to 1250mv

Anyone know where i can buy a custom 7970 VRM kit that fits on the reference cooler? The Artic one for VRM1 is garbage, VRM2 is 20c cooler! GPU is 40c cooler!

Edit- Yep, just benched 1300Mhz/1500Mhz in 3dm11 with 1.225mv... damn VRM