Off the top of my head:
BIOS (usually written in caps)
SCSI (pronounced 'skuzzy' but usually in caps)
lidar (usually lower case)
loran (seen both)
maser (usually lower case)
snafu (usually lower case)
TITSUP (usually upper case)
I reckon the only ones of those that qualify as words are maser and snafu (both are allowed in Chi, I'm pretty sure). I've never heard of most of the others.
Maser and
snafu are indeed allowed in Chi.
Snafu may even be common; I don't quite recall.
Lidar and
loran are also allowed in Chi, both classified as less common. An additional acronym word allowed in Chihuahua, is
asdic, which is something akin to sonar.
Asdic used to be classified as common, but no longer is.