ASRock P43Twins1600 Ram Problem

[1stgen7]

Just got my newly built computer up and running.
ASRock P43Twins1600 mobo
Intel E7200 2.53ghz (overclocked to 3.0)
XFX 9800 GTX+
OCZ Fatal1ty 2x2gb ddr2 1066 PC2(8500)

Everything seems to be working well, but I am having serious problems with the memory. First it only runs at ddr2 800. When I try to turn it up to 1066 manually in the bios it refuses to boot. I can deal with it running a little slower, but what I don't like is that it only registers as 3.18gb of ram in XP (and on boot screen). In the bios, it recognizes the full 4gb, but I can't seem to get it to work correctly past that. The timings seem correct, but I don't know all that much about timings. If anyone could help me I would greatly appreciate it. (First time computer builder)
Thanks,
John

 

[outlw6669]

A 32 bit Os, like Windows Xp, is only able to address a TOTAL of 4Gb of memory.
That includes the RAM, video RAM, BIOS, sound card and every other system device.
As such, you will NEVER be able to use the full 4Gb of RAM in a 32 bit Os.

In the BIOS, you will need to bump the RAM voltage to 2.0v, according to the Product Page, set the timings to 7-7-7-20 and manually set it to 1066Mhz. You can test for stability using Memtest86+ if desired.
If you are unable to run your RAM at 1066Mhz, you will see no performance drop running it at 800Mhz.
The only real benefit you get from the DDR2 1066 RAM is the ability to overclock far past 400Mhz FSB.

 

[1stgen7]

Thank you that is a big help. I am still a little confused because my roommate has almost identical specs but his 4gb of ram registers as 3.34gb in 32bit vista but maybe I just have more ram somewhere else.
Thanks for the timings, I think I must have looked at the wrong ram on their website because those were not the timings I saw previously.
I also sometimes get a memory error message in windows. If it happens again I will post the exact message. Thanks again for your help.
John

 

[o1die]

For a first time builder, you are lucky to have so few problems. My first build was a disaster almost 16 years ago. For the asrock, you're overclocking, so the memory may be overclocked also. Memory dividers are built into some board bios settings. So if your memory is set at 800, it's actually running faster if your cpu is overclocked. So the board compensates for the faster cpu fsb by reducing the memory setting so it's running within it's limits. Cpu fsb and memory fsb are tied together. Your bios may also have some preset configurations. My p45 asrock has 5 preconfigured settings, including ide and power saving. You might try one of these if you find this option; should be in one of the first two pages of the bios options.