motherboard problem or memory problem?

hey guys i have a lil problem that maybe some of you can resolve, i have an ASRock motherboard , Conroe865GV with pentium D 2.8Ghz and im using Major DDR 266 memory 1Gig 133 Mhz.

BEfore im using my memory in ECS 741gxm and it runs properly, but when iu use it to ASRock motherboard my memory turned down to 512Mb.

Ist a memory problem? A motherboard problem or is just not compatible??

actually it runs smoothly on other old motherboard that supports ddr 266, only got problem with new motherboard that supports also ddr266

I have an Asrock 775i65G, using the 865G chipset, and I use 2x256MB pc2100 (DDR 266) ram with my D 805. Runs flawless, in dual channel mode even.

At what speed is your ram running in the Asrock? Is this just one 1GB stick or two 512MB sticks? Have you tried reseating the ram?

If you've already checked all of those things, all I can say is that the 865 chipset is very picky when it comes to ram. In fact, when I want to test ram, I just use the integrated graphics found on my 865G, as it will blue screen Windows in minutes if the ram is not up to snuff. There should be a "compatibility mode" option in your bios that's supposed to help with ram compatibility. Make sure you have it set to ON.

Well i tried first the auto configuration option in bios for DRAM frequency, still got the problem, but when i choose manualy selection on DRAM frequency, still dosent work.