I realize it's been ~4 years, and the only explanation I have is that I was
feeling nostalgic, remembering better times in alt.sys.pc-clone.compaq,
wandering through the Google Groups archives when the subject of one of your
messages struck me as interesting. On November 2nd, 2004 at 8:17 PM, you
wrote:

Opened up the chassis and saw a Western Digital WD400BB disk drive in it.
Looked up the specs at the WD web site. Yep. 40GB. Great! More than
I'd bargained for.

The BIOS reported the drive manufacturer and model correctly, but
showed the capacity as 10GB.

Well, the same thing happened to me with an Evo D500 P4 I bought a few weeks
ago. It came to me sporting a Maxtor 6E040L0 "Diamondcrash" (so-called
because that's what every one of those things I've run into--including two I
bought new!--have done) drive.

Now, I know these are a 40GB drive. But this one only shows up in the BIOS
as 20GB, and sure enough, it's got a sticker placed over the real capacity
that shows it to be a 20GB drive. I know better than that.

Quick look around, time to make sure nobody's watching. It's only a Maxtor
drive, so I don't care if I diddle it in some interestingly fatal manner. I
whipped out a copy of HDAT2 and sure enough...the weasels at HP have set an
HPA that divides the drive right in half!

What's more, the Compaq BIOS Will Not Allow Any Diddling With The HPA. It
not only locks that out, but also blocks any attempt to send the in-drive
secure erase command. That was easy to work around--HDAT2 suggested booting
the system with the drive unplugged from the data cable at first...after
which I'd plug the cable in (how's that for trying?) and run HDAT2. It
worked. I now have a full 40GB paperweight. I will not dare trust this drive
or even use it although it does presently work. Too many bad experiences
with previous examples of the same thing...which was outstandingly bad even
by Maxtor standards.

Perhaps you don't have the system any more, perhaps you already know this,
perhaps you don't care...but what I really wondered about was this comment
that showed up later in the thread:

Pretty much what I've concluded, especially given that the DeskPro SFF
BIOS also seeems quite limited in its BIOS hard drive capacity

What was the limit...do you remember? I'm curious to know. I know I've run
up to 120GB drives on mine, and more than that once (320GB) Windows 2000 had
taken over from the BIOS and removed the 48-bit LBA limit. Most of the
machines I've got still have whatever BIOS they came from the factory
with...

William (computer/Usenet historian extraordinaire)