I have an ASUS PR-DLS533 MB, capable of up to 12 GB. I had 2 x 512KB sticks originally. RAM reads 1 GB. PC2100, ECC Registered DDR.
I bought 3 more 1 GB sticks (Brand A) and a single 1 GB stick (Brand B)
I installed, in pairs, two of the A sticks. Ram now reads 3 GB.
I installed, in pairs but not matched, stick A and Stick B.
RAM now reads 2.5 GB!
I have swapped the 1's all around, and it is definitely stick B that is the problem. My question is why?