For some reason, I can't set my 360 to 0800 mode to backup my games. It has an MS28 badflashed with Xtreme 5.2, and the 0800 disc I'm using is a Verbatim DVD+R DL burned with Imgburn. There are no problems I can see with the disc, and the 360 is visible to MTKflash, so I assume the connection and SATA drivers are fine. I've tried starting the 360 and putting in the 0800 disc with the SATA already connected and with it disconnected, I've tried removing the disc after 15 seconds and leaving it in, and I've tried booting the PC with the SATA cable connected and plugging it in after Windows boots.
When I boot the PC with the SATA cable in, Windows hangs for a few minutes while loading, and once booted up the drive isn't recognized. When I plug in the SATA cable after Windows is up, sometimes it freezes and other times it does nothing at all.
I'd try flashing the Xtreme0800 firmware to it, but I tried that yesterday with a different console and the flash just stopped at 66% on bank 3. So I'm understandably wary of trying that again. Anyway, I've spent the last two days scouring the net for any information on this, and I'm stuck. If anyone can help me out here, I'd appreciate it.

what sata are you using vt6421? if so which driver,

if you have sata driver on your MB you could try that (via is required only for flashing)
-soso

Yeah, I'm using VIA VT6421, with the latest driver from the website. I haven't tried it with the onboard SATA yet, had no idea it could work.

It worked! Holy CRAP thank you!

Enjoy,

-soso