I recently got a 5600+ Dual Core, It was doing all kinds of weird stuff in windows (with Trevius fixes too) or Linux. I always prefer Asus MB, this one was Asus - I found a nice app that came with the board, called "AsusUpdate" - updates the Bios in real time over the Internet. I guess the art of Bios updating is much improved since the old "floppy/update your Bios then throw the MB away " days
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Anyways, the Bios update with Trevius recommendations, and now it runs flawless.
Floppy Disks! I think I'll have nightmares tonight