I had the same on my usb key drive, i emailed the manufactures and below is there answer, i hope this explains your 8MB loss on your card
"With reference to your query concerning the 6MB memory loss
from your 128MB USB 2.0 Flash Drive. I know that this could be frustrating
for you. You buy a 128MB USB Flash Drive and you expect to get that product
with 128MB of memory. In theory you would, but unfortunately it doesn't
work that way. When it comes to electronic equipment not everything is as
If we do the maths it works out as this:-
128MB x 1024 x 0.95 divided by 1024 = 121.6 MB. This is the limit that
the capacity of the Flash Drive shouldn't go below.
128MB - capacity of the Flash Drive.
1024 - is how many Kilobytes in a Megabyte.
0.95 - is the 5% loss for the likes of the File Allocation Table (FAT) and
Table of Contents (TOC).