Ram Problem: Transcend 1GB Stick vs Xion 1GB Stick

[godling]

My friend has a motherboard with two DIMM slots. On one, he has a 1GB Transcend DDR2 667MHz single stick ram, the other is empty.

Today we went out and bought another 1GB stick, but not of the same company. It's from ZION, and it is a single stick 1GB DDR2 667MHz ram as well, so both of them are similar.

The problem is, the system boots with only one of them. If I put both into the two DIMM slots, then the system won't boot. If only one of them is put into ANY of the DIMM slots, the system boots fine. In other words, the two sticks are refusing to co-exist. (We have checked this multiple times).

What could be the problem? Timings and CAS Latencies? Isn't RAM of same type (DDR2) and same frequency (667MHz) supposed to work with each other seamlessly?

[DMB2000uk]

Do they have the same voltage spec?

And the what are the cas specs on each?

Try running both modules at the worst of the two settings (so the highest CAS and Voltage of the two).

Dan