I have an MSI 6990
http://imageshack.us/f/12/unlednfw.png/
As you can see here, i can put the mem clock Much lower, Or the core Much higher
Maybe MSI doesn't have this restriction.... I'll have to hunt one down. Too bad I've sold 5 of them already without trying them... (to pay for 2 sapphire 6990s I kept for myself LOL)
Appreciate you posting this!
I am more than certain that it's not my specific cards, Have you gone into MSIa and under the EULA and typed:
[ATIADLHAL]
EnableUnofficialOverclocking = 1
UnofficialOverclockingEULA = I confirm that I am aware of unofficial overclocking limitations and fully understand that MSI will not provide me any support on it
UnofficialOverclockingMode = 2
AccessibilityCheckingPeriod = 0
Once you do this you can set whatever clocks you want on whatever card you want, NOTE: MISa becomes very "tweaky" after you've done this, (EG: drag mem to lowest, Hit apply, Close misa, Reopen it, And it can go lower)
Yes, I surely do know how to use and setup/configure MSI AB for OC'ing. was one of the first things I learned when I started with bitcoins...
still, if you look through forums regarding 6990s you will see that people are unable to underclock memmory outside the parameters I mentioned.
I will hunt down an MSI board and see if it behaves differently. Will post back here, but it may really take a while...
http://www.newegg.ca/Product/Product.aspx?Item=N82E16814127574
Usin this one