Is it possible to reduce MEMORY voltage for AMD GPUs?

[bulanula]

5970/5850 3 phase, 5870 4 phase gpu.
The memory phase is located above the gpu phase on 5870.
You can undervolt the memory controller using GPUTool.
.95v is idle default.

Nice.  I will check that out for my workstation.  The bad news is my other 4 rigs are linux and GPUTool doesn't support Linux. 

Yeah. We need this tool for Linux.

Maybe it can be done with the BIOS as well

[ArtForz]

Okay, let me explain it again in SMALL WORDS.
VDDCI is memory controller voltage. Not memory voltage.
Memory voltage (MVDDC/MVDDQ) is from the 2 non-software-controllable VT243s (VT237s on 5970s).
Non-software-controllable. As in "needs hardmod to change".

now, on to VDDCI, which *is* software controllable on reference 5870s and 5970s.
It's already possible to play with it in linux with a trivial modification to radeonvolt as it's a vt1165 like VDDC, just at i2c addr 0x71 instead of 0x70.
So... how much power can you save lowering it? on a 5970 mining @ 300 memclock, reducing it from 1.05 to 0.90 drops total power/card by ~ 1W...
Yeah.

[bulanula]

OK.

So what are the VRMs that will get very hot on a 5870 reference that is mining at 960 core and 300 memory for example ?

Thanks ArtForz !