Mobo slot 1 = bad performance suddenly

When I plug my SATA HD into slot 1 of my PC’s mobo (as opposed to slot 2), the following occur:

-boot time doubled
-choppy, unresponsive behavior during high-cpu usage
-flaky audio in/out
-lag during gaming significantly increased
-HD benchmarks awful (details and more below); other benchmarks fine

Also possibly related: The secondary hard drive stopped functioning properly last weekend (would hear series of faint noises like beep-click); eventually I would hear the platters stop spinning during operation. This hard drive is no longer plugged in. Selected data was lost; scandisk could not help.

Passmark performance test showed major differences in the hard drive’s performance:
Scores for SATA slot 1 / slot 2:

Disk - Sequential Read 3.3 / 46.4 (!)
Disk - Sequential Write 3.4 / 47.3 (!)
Disk - Random Seek + RW 1.8 / 2.9

Other diagnostics

Memtest86 - 4 passes with no errors
Scandisk - no errors
Voltage readings - within range
Banging head on case - no results available

Pentium 4 CPU (2.4C with hyperthreading) Socket-478
Abit IS7-E with fail-safe settings
1 Gig Ram (4 X 256)
Antect 430 W Power
Windows XP Pro
Dual LCD Monitors
9700 Pro video

Any help would be appreciated!

a bios update might help

Not sure how Windows deals with SATA devices but if it was an IDE devices that had read or write problems it would probably drop the DMA mode of the device down to PIO. The symptoms of this are exactly what you are experiencing.

The solution for IDE devices is to delete the IDE controller in Device Manager (for Primary or Secondary). Maybe the same works for SATA devices.