Reported memory size

I occasionally come across situations where reported memory size is half of what's physically installed. For instance, I had a machine with 64mb of PC100 ram and I installed another 64mb stick (different brand) but the reported size was only 96mb, not 128 as expected.

On another machine, it had one stick of DDR2100 128mb, but was only reporting 96mb??

These reported sizes are on POST and using Memtest.

I have always used 'same type' and 'same speed' as the basic rules of thumb when adding memory - is there others I should know about?

Cheers,
Brodie

 

The only thing I can think of is you have onboard video which uses part of your system ram making it unavailable to the system therefore not reported by the system.

 

32 meg missing from both machines. Yep onboard video.

 

WOW! 3 replies in half an hour - I think I will enjoy this forum.

I can understand the incompatibility bit, but in the case of the pc with the single 128m chip that reported only 96, surely the onboard video wouldn't be claiming 32mb. Could it?

Cheers,

 

Yes it can, and will. What is the size of your video ram? If it is 32 mg there is your missing ram.