Having difficulty underclocking my memory below 1375

[BigBoote]

Hi,

My setup:

Intel Q6600
Asus P5K-E (a 16x PCI-E slot & a 4x PCI-E slot)
Antec HCG-900
Sapphire 6970 (x2, no crossfire cable connected)

Driver version 8.85-110419a-118226C-ATI

I'm using Catalyst Control Center (latest drivers) and Trixx.  I've read elsewhere people underclocking their 6970 memory way down to 500, but CCC doesn't let me go any lower than 1375.  In Trixx, I can set the memory to 500, but I don't think this is being honored; using GPU-Z shows the memory speed still at 1375.  Is there another tool I need to use?

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[lessPlastic]

I may be wrong, but it seems you are confusing shader/memory/core memory clocks. Typically underclocking doesn't third the speed, it'll take it down by 10-20%.

[Elokane]

Use MSI Afterburner or AMD GPU Clock tool.

[BigBoote]

I tried AMD GPU Clock tool - it appears to be incompatible with the 6970.

MSI Afterburner seems to be a much better product that Trixx, however, it still doesn't reduce the clock below 1375.  It allows me to do it, but as soon as I start mining, it reports the speed at 1375.

Also, changing the sliders on Afterburner and/or CCC seems to be a ticklish affair - I will move the slider and one second later it moves back.  Is there a way to make sure that only one of the tools is controlling the cards?  This happens even if I use task manager to make sure that CCC.exe is not running.