If your bios allows, up the mem voltage slightly or loosen the mem timings a little. This is not unusual when running 4 sticks.This can be most efficiently tested for with memtest86+, a small program that can be run from a dosboot cd or floppy. Memtest86+ is also one of the programs on the "Ultimate boot CD" (a invaluable diagnostic tool) under file systems last I checked.
I haven't found a way to change voltage, but I have played with the timings -- my experiments did not change anything.
I have used a Windows system test utility for measuring memory speed -- and what is interesting is the the speed is either a full
4880MB/s or exactly one fourth: 1220MB/s, and with all 4 memory modules installed I get the slow speed in most of the tests, while with only 2GB installed (any two of the modules I have) I always get the fast speed.
I am seeing the slowdown when all 4 modules are installed both under Windows and Linux.
I have run the MemTest86 utility that got installed on my hard disk with Linux, but after 5 hours and only 30% passed I cancelled it.
I simply do not understand how the same memory works if I only use modules and obviously does not work correctly when I use all four.
Is this something that others have experienced? Could this mean that my motherboard is damaged? Since 2GB work, no matter which modules I use, it cannot be the RAM, no?
I am pretty much a layman and newbie when it comes to hardware though ...