Underclocking 7950

[Igotcha]

Hi,

I try to underclock my Sapphire 7950, it's this model:

SAPPHIRE TECHNOLOGY Grafikkarte Radeon HD 7950 BOOST - 3 GB GDDR5 - PCI-Express 3.0

I tried the method from this thread https://bitcointalk.org/index.php?topic=111891.0, but I am still not able to change the "Core Voltage". Is this setting hardware locked for this model?

Thanks!

[Igotcha]

It seems that I can change the Core Voltage with TriXX, but not with MSI AB.

Default settings are:

GPU: 1.100
Memory Clock: 950
VDDC: 1.250

My cards are working with these cgminer settings at the moment with 540Mh/s each:

-I 7 --auto-gpu --auto-fan --temp-target 70 --gpu-fan 40-90 --gpu-engine 600-1100 --gpu-memdiff -150

Any recommendations about settings for TriXX with the targets:

• keep at least the 540Mh/s
• reduce Voltage
• reduce fan noise

[mt_bird]

You can reduce fan noise by increasing target temp: --temp-target 80, for example. No need to run the card at 70C. 80-85C is still perfectly safe and the fan will be quieter and last longer.

[grue]

You can reduce fan noise by increasing target temp: --temp-target 80, for example. No need to run the card at 70C. 80-85C is still perfectly safe and the fan will be quieter and last longer.

can't you just force the max fan speed to something low?

--gpu-fan 30-40

[Igotcha]

Wow thanks, I set temp to 80 and almost needed to check if the cards are still running, because they are so quite now 

Can you give me a hint regarding the Core Voltage too maybe, or can I get more than these 540 and still keep the cards silent (silent != vacuum cleaner)?

You can reduce fan noise by increasing target temp: --temp-target 80, for example. No need to run the card at 70C. 80-85C is still perfectly safe and the fan will be quieter and last longer.

[mt_bird]

Wow thanks, I set temp to 80 and almost needed to check if the cards are still running, because they are so quite now 

Can you give me a hint regarding the Core Voltage too maybe, or can I get more than these 540 and still keep the cards silent (silent != vacuum cleaner)?

You can reduce fan noise by increasing target temp: --temp-target 80, for example. No need to run the card at 70C. 80-85C is still perfectly safe and the fan will be quieter and last longer.

Well, my cards run stable with --gpu-vddc 1.125  at 1100 MHz core clock. You may need to experiment a bit to find the lowest voltage for stable operation at your desired clock.

[Igotcha]

Hi mt_bird,

can you post your complete cgminer settings please?

I am not very familiar with under/overclocking and these settings.

Thanks!

Wow thanks, I set temp to 80 and almost needed to check if the cards are still running, because they are so quite now 

Can you give me a hint regarding the Core Voltage too maybe, or can I get more than these 540 and still keep the cards silent (silent != vacuum cleaner)?

You can reduce fan noise by increasing target temp: --temp-target 80, for example. No need to run the card at 70C. 80-85C is still perfectly safe and the fan will be quieter and last longer.

Well, my cards run stable with --gpu-vddc 1.125  at 1100 MHz core clock. You may need to experiment a bit to find the lowest voltage for stable operation at your desired clock.

[mt_bird]

Hi mt_bird,

can you post your complete cgminer settings please?

I am not very familiar with under/overclocking and these settings.

Thanks!

Wow thanks, I set temp to 80 and almost needed to check if the cards are still running, because they are so quite now 

Can you give me a hint regarding the Core Voltage too maybe, or can I get more than these 540 and still keep the cards silent (silent != vacuum cleaner)?

You can reduce fan noise by increasing target temp: --temp-target 80, for example. No need to run the card at 70C. 80-85C is still perfectly safe and the fan will be quieter and last longer.

Well, my cards run stable with --gpu-vddc 1.125  at 1100 MHz core clock. You may need to experiment a bit to find the lowest voltage for stable operation at your desired clock.

Hi,
The following settings work for my Sapphire 7950. I am using Linux, though, so there could be differences if you are on Windows. I need to use powertune 20 or else my card's clock won't stay at 1100, but you might not need it:

--temp-target 80 --temp-overheat 87 --temp-cutoff 91 --gpu-engine 1100 --gpu-vddc 1.125 --gpu-memclock 950 -I 7 --auto-fan --gpu-powertune 20

[Rjb82]

i have a voltage locked 7950. While i cant directly change the voltage, there are certain thresholds present for the card to lower the voltage on it's own. kinda like when the card switches between 2d and 3d mode.

i think the card is stock @ 1ghz, and IIRC the card lowers the voltage @ 800mhz core (1.125v) and 600mhz (1.050v, i forget what it was honestly).

I haven't run into the need for this yet, but noticed it when playing with the settings.

[Igotcha]

My cards run fine now with the vddc settings from mt_bird.

As I said, this is just a try to keep the hashrate but to save some power consumption. I can see that the actual vddc is lower than the stock 1.25 but varies from 1.08 to around 1.18 - maybe a little saving  

The main goal was to reduce the fan noise and with the temp setting and the vddc everything is fine now.

[shilex]

how mutch hashrate are you getting, i have the same one and i run 520mhs at 990/625....

[Igotcha]

With these settings they run around 540-555Mh/s.

how mutch hashrate are you getting, i have the same one and i run 520mhs at 990/625....

[shilex]

and how about the temps at that clock speed?
are the cards in risers or?

[Igotcha]

The cards run at 80° now and they are on risers (unpowered).

and how about the temps at that clock speed?
are the cards in risers or?

[bitcoiner49er]

I just ended up using cgminer to underVOLT my cards.

1100/300 @ .975V = 600-605 MH/s each running 72-74C with 65% fan.

[linc0ln]

simply question:
You have marked all in settings>general>compatibility properties? You change from user mode to kernel mode?

[Igotcha]

If you mean me, yes.

No effect, voltage still disabled.

With TriXX it seems that I can change the voltage settings.

But my actual question is now: When I set the settings with cgminer command line parameters do JUST THESE settings affect the voltage settings, or is it a MUST to change them via MSI AB or TriXX?

simply question:
You have marked all in settings>general>compatibility properties? You change from user mode to kernel mode?

[bitcoiner49er]

If you mean me, yes.

No effect, voltage still disabled.

With TriXX it seems that I can change the voltage settings.

But my actual question is now: When I set the settings with cgminer command line parameters do JUST THESE settings affect the voltage settings, or is it a MUST to change them via MSI AB or TriXX?

simply question:
You have marked all in settings>general>compatibility properties? You change from user mode to kernel mode?

I set all my parameters in the cgminer config file.
Verify those settings using GPU Caps Viewer.
Done.