Ubuntu 10.4 64 bit OS - 8GB RAM is shown as 7.8GB - why? where is the rest gone? or is it just my math?
You might find the .2gb is being eaten by intergrated graphic or similar.
To find out where it's going run:
gigabyte (GB) 10^9 2^30 gibibyte (GiB) 2^30
The manufacturer has supplied 8 * 10^9 Bytes of storage and marketed it as 8 GB.
8 GB * 1000 = 8000 8000 / 1024 (actual base two representation) = 7.8125 GB
Whats worse is if they actually did this the whole way:
Its the same way with Harddrive manufacturers.
And ISPs: a 20 meg connection is 20 million bits not bytes. In reality since 1 byte = 8 bits, its only a 2.5 MB connection rate at maximum.
It's due to the 3GB limit, PCI, AGP and PCIe and the hard drives, USB controller and any other PCI device you can think of.
This actually eats 0.5GB+ of RAM space but it's remapped higher in RAM space, above 8GB because Ubuntu supports 64GB (maybe only 16GB, but it's remapped). I'm guessing 1.2GB of RAM is eaten by PCI devices and 1GB is remapped.