Underclocking 6990s 100mhz past core clock. Is it possible with stock bios?

[CrazyGuy]

I'm using linuxcoin and I've tried atitweak,aticonfig, and AMDOverdriveCTRL. All tools will show me that they have set the memory clock to whatever I want, but once I put load on the card, mem clocks shoot up to 1250(If the mem clock is over 100mhz below core clock). After doing some research it looks like quite a few people have run into this issue.  Has anyone gotten past this issue without flashing the bios?