I hope you are using a motherboard which supports Dual-channel architecture.The
proper configuration for your motherboard is 2 DIMMs or 4 DIMMs, NOT 3 DIMMs
(unless you use a motherboard which supports a triple channel architecture).
For dual channel configuration and best performance DIMMs (dual inline memory
module) need to be installed in pairs.
e.g. look at the pic of dual channel memory slot shown below.
The colors indicate which bank they belong to, bank 0 or bank 1, e.g. lets
assume orange is bank 0 and yellow is bank 1.
Then one can place a matched pair of memory modules in bank 0, but a
different-capacity pair of modules in bank 1, as long as they are of the same
Using this scheme, a pair of 2 GB memory modules in bank 0 and a pair of
matched 4 GB modules in bank 1 would be acceptable for dual-channel operation.
Modules rated at different speeds can be run in dual-channel mode, although the
motherboard will then run all memory modules at the speed of the slowest module.
suggestion:Don't try to mix and match 3 different types and 3 different sizes of RAM.
you may try
remove each stick and run them
independantly to see if you have a bad stick or bad dimm slot
also check if you have 2gb allocated to your onboard video.