Corsair Dominator 8500 strange problem

[mintcake]

Hello,
I recently bought an extra set of RAM ( 2x2gb Corsair Dominator 8500 1066) to upgrade my current to 6gb ( original 2gb are of same dominator)...
I actually had 4 gb installed but took two out to make room for the new 2gb sticks.

Now the originals were clocked at 1081 and running perfectly fine, so i removed two sticks and placed the new ones in slots 1 and 3 respectively so the banks were matched, now it all seems fine in the bios etc and it was clocked @ 1081 so i booted to vista 64 and it just locked so i thought hmm strange so gave XP 64 a try which was fine for a few minutes but once i started running any thing it just shut down the machine so i clocked the ram down to 900 as i can only go from 900 to 1081 as my cpu is clocked @3.6.
My borad is a rampage formula x48
cpu - q9450
psu - corsair 650w
gpu - 3870x2
there is a physx ppu in there also
and about 4 cooling fans of varied size
3x hdds
Dvd

I tried upping the voltage to about 2.13 which did not help at all....
could it be that i cant have it running at 1066 and above with that amount in?
admittedly i have not set it to 1066 as that would mean having to clock my cpu down which i dont want to do, i am not sure if there is a way of keeping the cpu at this level and clocking the RAM independently!!!
could it be a power issue?
any help would be greatly appreciated.

 

[mintcake]

UPDATE: just had a look on ASUS's support forum and there is an 0803 bios now out which seems to fix some memory issues going to give that a try, but i am still open to suggestions if there are any.

 

[Yellowbeard]

Mixing 2 different densities of modules can cause instability and is not recommended. However, it may work with a bit of BIOS tuning. You are most likely going to need to increase your memory controller voltage 1-4 steps above the stock setting to compensate for the load of 4 modules.

I'd start by downclocking the FSB to hit about DDR800 or so and try to clock back up from there. If your board allows it with that CPU, you may try playing with a different divider on the CPU to give you more flexibility on the memory frequencies you can choose.