Undervolting and underclocking a 7870 Tahiti

[superarthur]

Hi all,

I've got a new Powercolor 7870 Tahiti. I got around 425 Mhash/s using GUIMiner, but the temperature went up to 92C.
I am thinking maybe I should undervolt and underclock to keep it below 80C.
I have no prior experience in over/underclocking.
Can someone please give me some advice?

Thanks,
Arthur

[Magnate]

try using MSI afterburner, and enable the voltage unlock function in the setting button.

Just experiment with turning the voltage down until it is not longer stable, see what effect it has on heat.

Frankly going to 92deg suggests the heat sink and fan is really struggling, surprised it didn't shut down. I assume you have auto fan enabled!?!

[HellDiverUK]

92C there's something wrong somewhere, either the heatsink is clogged with dust, the heatsink isn't mounted well on the chip, or your fan settings are wrong.

Even my horrendously overclocked HD6970 runs at 85C with only 65% fan speed.  If I could bear the noise of a 100% fan it'll run at less than 60C.

The old HD5870 I got ran up in the 90C area, turned out the previous owner had stripped off the factory TIM and put on some shitty silver stuff, it was like glitter mixed with butter.  Horrible stuff.  I replaced it with some ancient old white compound (this stuff came in a tube in the 80s and was for mounting heatsinks to TO-220 transistors to heatsinks).  Now it runs around 75C.

[superarthur]

It only goes to 92C when mining. The idle temperature isn't high at all.

It's a brand new card. Haven't tweaked anything yet.
I have a micro-ATX case with only one case fan, so the air flow isn't the best.

[gbx]

It only goes to 92C when mining. The idle temperature isn't high at all.

It's a brand new card. Haven't tweaked anything yet.
I have a micro-ATX case with only one case fan, so the air flow isn't the best.

open the case and put a box fan on it or something.  you should be able to get the temps down.

[greaterninja]

Here is a screenshot Powercolor 7870 running 510MH/S   at 72C.

It shows my settings as well.



The power and fan settings and manual fan setting is KEY.

Fan:  90%
GPU:  1210MHZ
Enable manual Fan Control - Checked
Enable Graphics OverDrive - Unchecked, correction*  i think graphics overdrive needs to be checked actually.
Power Control settings:  -8%
TEMP:   72C
Hashing Power  :  511.4 MH/s
Video Card:   PowerColor 7870 Myst Edition (TAHITI LE  - 1538 stream processors unlike the 7870 with 1280 stream processors).
Cost:  $208 at newegg.com brand new with games.

[superarthur]

Thank you all for the replies.

After installing a case fan, the temperature only goes to 83C if I run it without flags.
Running with -v -w 256 (or 128) gives me a lower hashrate, but also a lower temperature (79C).
Haven't tweaked other settings yet.
Is the CCC power control as good as undervolting with Afterburner or Trixx?

[greaterninja]

Thank you all for the replies.

After installing a case fan, the temperature only goes to 83C if I run it without flags.
Running with -v -w 256 (or 128) gives me a lower hashrate, but also a lower temperature (79C).
Haven't tweaked other settings yet.
Is the CCC power control as good as undervolting with Afterburner or Trixx?

i got the same exact card as you.  just use my settings like in the screenshot.  use -8% power   and well your GPU mhz will vary.

good luck man.

[Cereal]

Here is a screenshot Powercolor 7870 running 510MH/S   at 72C.

It shows my settings as well.



The power and fan settings and manual fan setting is KEY.

Fan:  90%
GPU:  1210MHZ
Enable manual Fan Control - Checked
Enable Graphics OverDrive - Unchecked, correction*  i think graphics overdrive needs to be checked actually.
Power Control settings:  -8%
TEMP:   72C
Hashing Power  :  511.4 MH/s
Video Card:   PowerColor 7870 Myst Edition (TAHITI LE  - 1538 stream processors unlike the 7870 with 1280 stream processors).
Cost:  $208 at newegg.com brand new with games.

https://i.imgur.com/nuzy3AU.png

You should try to put your mem speed at GPU-150. So 1060.
Your mem is now at 1500..

[greaterninja]

Here is a screenshot Powercolor 7870 running 510MH/S   at 72C.

It shows my settings as well.



The power and fan settings and manual fan setting is KEY.

Fan:  90%
GPU:  1210MHZ
Enable manual Fan Control - Checked
Enable Graphics OverDrive - Unchecked, correction*  i think graphics overdrive needs to be checked actually.
Power Control settings:  -8%
TEMP:   72C
Hashing Power  :  511.4 MH/s
Video Card:   PowerColor 7870 Myst Edition (TAHITI LE  - 1538 stream processors unlike the 7870 with 1280 stream processors).
Cost:  $208 at newegg.com brand new with games.

You should try to put your mem speed at GPU-150. So 1060.
Your mem is now at 1500..

What do you mean drop my memory speed to 1060?  How do i go about doing that if its at 150 which seems to be lowest so far?

[superarthur]

Thank you all for the replies.

After installing a case fan, the temperature only goes to 83C if I run it without flags.
Running with -v -w 256 (or 128) gives me a lower hashrate, but also a lower temperature (79C).
Haven't tweaked other settings yet.
Is the CCC power control as good as undervolting with Afterburner or Trixx?

i got the same exact card as you.  just use my settings like in the screenshot.  use -8% power   and well your GPU mhz will vary.

good luck man.

I just tried it after leaving the last post. It actually went to 525Mhash/s without any flags. (With my Nvidia card, -v does help improving my hashrates, but setting any flags to my AMD card just slow it down.)
However, it went back to near 90C.
With the GPU clock lowered to 1150, I can do 500Mhash/s in the mid-80Cs.