Odd problems after memory upgrade

[johann_p]

I have recently bought a 2 GB memory kit to upgrade my memory from 2 to 4 GB. Since then, I had problems of the odd kind: computer behaving slugglishly, slow, long waits, but not always. Sometimes problems to shut down, overall sluggish and unstable feeling.

Today I did some systematic tests and found that the memory bandwith is erratically changing from 4880Mb/s to 1220Mb/s ... randomly in about 4 out of 10 tests.

I then started to swap the memory: there are 4 slots, labeled DIMM0/DIMM1 and channel A/channel B.
DIMM0 is marked blue and DIMM1 is marked black. Originally I had, as required, the two 1GB RAMs in the two blue DIMM0 slots (everything worked fine then), then I installed another two 1GB RAms into the black DIMM1 slots and since then I have those problems.
The original thesis was that the new memory is bad, but when I placed the new memory into the DIMM0 slots and removed the old memory, everything was fine too. Testing each single RAM in DIMM0/Channel A also produced no problems.

The problem only exists when all 4 slots are filled. So this is not a problem of the RAM modules, but of the fact that 4 instead of just 2 slots are filled!

All four RAM modules have the same spec DDR2 8000 5-5-5-12 and are from the same brand company.

The motherboard is an Intel DG965WH with the newest BIOS.

For me, this does make so not sense, but the problem can be repeated -- I have removed 2 GB now and everything is fine again (except that I would need that additional 1.5GB I would get for the work I do on that machine)