DDR module underreporting

SCRawl · Post by **SCRawl** » 2006-07-26 05:35pm

I just recently inherited an older AMD system (a 1.5 GHz Athlon), and both CMOS and Win2k report it having 96MB. (I know that this isn't enough, but that's not my point.) My point is that this thing has only one memory module. I pulled the module, and it claims to be 128MB. I've run memtest on the thing, and it also reports it as having 96MB, but reports no errors.

I switched the module from one bank to the other, and get the same result. My first inclination is that the module is damaged.

This sort of thing is outside my experience. Is it common for RAM to be damaged enough to underreport its size, but still function?

Chris OFarrell · Post by **Chris OFarrell** » 2006-07-26 07:24pm

Destructionator XIII wrote:The system might have an integrated video chipset on the motherboard. These integrated chips 'share' main memory with the rest of the system. What happens is they take a chunk of the memory all to themselves (in the BIOS usually), and hides it from the rest of the system.

Odds are the missing 32 MiB are for shared graphics memory.

Ja. 32 MB is just too even a number for that to be a coincidence. If it was like 23.654 or something, okay, but odds are that the system is steeling 32 megs for something.

SCRawl · Post by **SCRawl** » 2006-07-27 03:14pm

The motherboard manual confirms your theories, although it's not exactly in an obvious part. It is possible to change the amount of shared memory, and I think I'll drop it down a bit until I can get some more system memory.

Thanks for the help once again.