Because there is no direct disk access, anymore (except maybe in Linux with some special config/param). Its all handled through BIOS disk services (e.g. INT13 and such). When you change the BIOS or controller option ROM, there may be changes to the geometry and alignment support used for disk access. MBR fix might solve it, might not.
First off, you are a genius in
my book for modding this BIOS like this.
However...
I also tried to add a WD7500AADS to my system, a GA-7N400 Pro2 v2.0 with a 320 GB PATA bootdisk and a WD6400AACS SATA data disk.
At first, the system kept freezing right after recognising the 750 G disk, no matter which port I connected it to. I even went back to the store to have it replaced, since the 640 G disk was recognised just fine!
When the replacement disk refused to cooperate as well, I started the Google, and ended up here. I couldn't believe my luck! I flashed my BIOS, installed the new disk, and voila! I had 750 G of additional diskspace! Or so I thought...
The first thing I noticed, was the fact that the reported sizes of both disks appeared to be reduced by almost 8% : down to 698 G and 589 G respectively, according to the POST messages...
WinXP didn't seem to mind, though, and installed the new disk properly. The next step was Ghosting the bootdisk to the 750 G Disk. Still, no problem. 3 bootable, primary partitions and 1 big logical partition, all in one go, leaving plenty of unallocated space for the next step. Checking the result in WinXP made me go :hmm: for the first time: Paragon HD Manager 2006 reported both big disks as "WDC WD6400AACS-00G8B1"
In spite of the confusing descriptions, both disks were the right size, so I didn't pay too much attention to this. Boy, do I regret this now...
I removed the original bootdisk and set the BIOS to boot from the 750 G disk. It booted right up, however, a few programs had trouble finding essential files to get started. Most worrysome was the fact that my mailclient, Forte Agent 5.0, which is installed entirely on my second disk D-partition, acted like a fresh install, even requiring me to re-enter the activation-key. The kicker: all my mails were nowhere to be found! Thank God for back-ups!:whiste:
After some damage-control, I noticed that the first partition on the second disk was reported by Paragon HD Manager as being "Unallocated". Partition Magic even reported a completely corrupted partition-table! Still, all three partitions (D primary, E and F logical partitions) on that disk remained accessible under WinXP, so I decided to backup the data to the first disk, and recreate the partitions from scratch. After copying partitions E: and F: to the free space on the first disk, I decided to delete both partitions and the extended partition that contained them. Within a second of clicking the "Apply"-button the screen went black, and my computer rebooted.
The D partition was now completely gone, even in WinXP, but somehow partitions E: and F: were still there! Even "Undelete" from Paragon HDM couldn't find a single trace of the vanished D partition.:'(
I'll spare you the language my lovely wife was forced to endure, but after cooling down a bit, I questioned the Google once more, and gave EASEUS Partition Master a whirl. This program appears to have rescued more than 99% of the missing files, if not everything.:awe:
But here's the rub: how does the modded BIOS handle 2 disks with different geometries? Is it possible to control 2 different disks in a non-RAID situation? I made sure to use the BASE-BIOS and the BASE-drivers, but still came very close to a giant data-disaster!
I will post a follow-up with a few more points I encountered, but these are my first experiences with this, still very impressive, modded BIOS. I hope someone benefits from them, and posts here too.