I am having a few problems upgrading my memory. I recently bought a new stick of 512mb DDR400 ram to upgrade to 1024mb. For some reason my bios will not detect the extra ram. Both memory sticks work by them self in every slot but will not work togther, the memory test always comes up with 512mb. I have exchanged the new ram with a different brand but still the same. I found out later the when I cleared the CMOS by removing the battery, the bois detects the full 1024mb on the memory test but gives a message saying "CMOS Checksum error loading defaults". if I enter the setup i can see 1024 but when I save and exit, continue to windows it keeps on revirting back to 512. I simply cant get into windows with 1024. I am hoping this is not a mother board problem. I have tryed falshing the motherboard with the new bois, but still the same result. My Specs are AMD 2600+ GA-vt600 -L MotherBoard 512DDR400 PQI PC3200 512DDR400 Hynduai PC3200

Check your manual/specs... Some boards, even though they have three RAM slots & advertise support for DDR400, will only support one stick of PC3200 (DDR400), two sticks of PC2700 (DDR333), or three sticks of PC2100 (DDR266). I don't know if that's the case with your board, but it's a possibility.... Asus A7N8X-X 1800+ @8x210mhz 512mb PC3200 Ti4200/8X 128mb WDC 60GB

Jam's correct about the DDR400 issue and if this is the case with your board you need to go into the bios and there will be an option to change the ram to run at 333 or 166 which is the same 166x2=333 it just depends how your bios represents it, also there are 3x types of 2600+, one of them running at 266 or 133x2, so if your chip is this one then change the ram to run at the speed of the chip, you want a 1:1 ratio for best performance, checksum error means that you need to go into the bios and alter the settings because after removing the battery or resetting cmos all your options will have been lost, you need to enter the bios and change the settings, its also possible that the modules might not be compatible with your board or not compatible with each other, i suggest trying different combinations of slots and trying 1 stick at a time Q-TEC 550 Watt PSU MSI VIA KT4AV-L 2800+ Barton 512 DDR333 GeForce4 Ti 4200 128Mb Aero 7 Lite 80Gb Samsung ATA133 HDD 120Gb WD ATA100 HDD LiteOn LDW-851S LiteOn LTR-52246S

G'day fellers Finlaly have fixed this problem. Not sure eactly how but I am in windows with 1024mb. I loaded bois with supposely fail-safe defaults. when the computer restarted nothing was working at all, just a black screen. So I reset CMOS again and went into setup when i get the checksum error. i choose the to load the failsafe option, but then had a look at the advanced chipset features and found something called "banking interleaver disabled" which i new had to be re-enable, cuase it always was. When i saved and exited the checksum had disappered and i could get into windows with full memory. Probably some other options that have changed in bios, thats why i have now full memory.. The ram freq is still set to auto in bois which it was before... Will have to investage further as to what as changed.