Asrock 939 Dual Vsta memory problems

[allanco]

Hi All, my first post, and though I am not a complete noobie when it comes to building pc's, I am pretty clueless when coming to memory problems.
Having searched here and elsewhere I can see that the 939 Dual Vsta board is quite picky when it comes to memory, which probably explains my problems.

I have two sticks of Crucial DDR400 512MB (matching pair and according to Crucial compatible with this board).
However the pc will only go as far as a blue screen upon booting and will continually boot,close, and restart (the blue screen doesn't stay up long enough to read what it says)
They will both work fine if installed individually and both work fine on a Chaintech board.
The problem I have is that I don't know a thing about timings etc. and what to set in the Bios, so can anyone give me a clue, or point me in the right direction?
I have e-mailed Asrock support and Crucial but neither have yet to answer (4 days, so maybe they still will)

[daiphuoc]

put it in Async if you haven't done it already, I had kind of similar problem but not exactly, see if it works

[Tweakurr]

The bios settings when left in AUTO normally go with conservative settings. However, you might want to set them manually to math the recommended speeds for your memory. The order of presentation in the bios does not match the speed listing. In other words if you want 2.5, 3, 3, 7 - the 7 timing won't be the 4th one listed. Pay attention to the name of the timing adjustment and also set the last one to 2T. Some memory sticks won't handle 1T on these boards. Also some people have complained using the highest memory voltage keeps them from booting, so play around with those a bit. Did you go over my FAQ sticky for this board?
You may also want to try putting the sticks in the alternate memory slots to see if the board responds better.