Undervolting
Hi all,
I have been a long time reader, following this thread closely, and having gotten so much out of this forum with a successful unlocking of my VTX3D 6950, I thought I'd give something back to the community.
While everyone has been talking about overclocking and how to get the fastest speeds possible, no one, has been exploring undervolting.
Now that I have gotten my 6950 into a 6970 and overclocked to speeds I am comfortable with in the games I play, the next logical step is to look in the other direction -> undervolting the 2d or idle speeds.
Why? you ask.
Because the usage of my PC is for more than games, where the overclocked speeds are needed. The PC is used by me and my wife to read emails, surf the web, work related activities, Word/Excel/Powerpoint, shopping, banking, etc.
That means the vast majority of the time the PC is in 2D mode.
Everyone is whinging about high temps. Here is a couple of ways to help reduce the temperature. UNDERVOLTING the 2D idle speeds. This in turn reduces the heat produced as a by-product. The other way I reduced temps was to replace the thermal paste on the card, my card was thick with TIM. I cleaned and replaced it with some Arctic Silver 5 I had laying around. This reduced temps in the order of 4-5 degrees C. Not bad for a free mod.
We know that the 69x0 goes into an idle speed and voltage when in 2D mode, doing nothing.
The card downclocks itself to 250 core and 150 memory speed using 0.9volts.
Does the card really need 0.9v to run in Windows?
As no one had done this before, I bit the bullet and tested it myself. (Believe me I searched all over the net for a similar instance).
The lowest you can go without artifacts in 2D is about 0.76 volts. But I'd run it with 0.77 volts, just in case. This was adjusted using RBE v1.27, and VID3 was adjusted accordingly in GPU registers. Running any lower than 0.76V will lock the PC up upon boot up. You will get as far as the windows startup screen, and as soon as the display drivers are loaded you will crash to a black screen. Running at 0.76volts I experienced artifacts on the Windows desktop. So 0.77v it was.
I'm now running my 6950 with 0.77v for the 250core/150mem speeds.
Which is good for 5 to 6 degrees C lower in heat.
Also note that the voltage and temp change is observed in MSI Afterburner 2.1.0 beta 7. Unfortunately, GPUZ ver 0.5.1 does not pick up the change. I think, GPUZ is reading the value off the driver, rather than the bios. However, the lower temperature is picked up by GPUZ as well.
6970's might need a bit more volts in 2D mode, but some tests are needed there.
Good luck.
Clearly this is for people that know what they are doing ONLY.
You need to know how to change VID3 using RBEv1.27.
You need to know how to extract and reflash the updated bios onto your card. (I used the scripts for unlocking the 6950 to a 6970 downloaded from this very site).