I've tried it with another cable and also a sata drive with a sata-to-ide adapter, so 3 different drives now. Also, all of them show up and work in WinXP (another sata drive) on the same pc, not to mention the original one was working without any issues so recently.
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I've tried it with 3 different ide cables now, one brand new asus sealed, just opened the baggy now, still no luck.
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Just tried both the hdd and one of the "suspected culprit" cdroms in another 865g socket 478 mobo, and everything boots and installs fine. Go figure. Still would love to hear any ideas as to what could be happening with that p5pe-vm board, since now it seems like that's where the problem is.
And just to get some things out of the way, with the p5pe, I've tried resetting the cmos several times, starting the pc without the cmos battery, tried few of the various dma modes in the cdrom bios settings (with the pio mode set to 0 the system would properly freeze trying to load the cdrom driver), finally reflashed the bios again to 1501 (the last version, same as I had before though). Tried 2 different ram kits, with both 1 and 2 sticks (512 and 256mb). I can't believe it could be related to the board currently running a c2d (and I know it can't, it was fine a few weeks ago), because that is the only thing that I haven't tried swapping out for something else.