Well, I hope it's not a design flaw as iirc I have the same board in a rig of mine (doesn't have any such issue though). I don't use it for gaming anymore though, it's been relegated to my bedroom for watching DVD's 😁

I've used it for years as my main computer without issues (and with a 6800 ultra), this started somewhat recently.

Just a little update:

I got an old case "from the trash" at the university. Missing some 5 1/4" bay covers, but other than that, it is just fine, so I decided to give the K8V-X SE another go. This time around I decided to give it full treatment. Removed everything, including the chipset heatsink, washed the board (just water, and then used isopropy alcohol on spots I wasn't happy), cleaned the processor and heatsinks with isopropyl too and assembled everything back together while applying a good quality thermal paste (Arctic Cooling MX4). Since I do not have my GT6600 at the moment, I put an old MX440 on the system and called it a day.

Now the results: The SATA bootrom doesn't work, so I had to use a cheap SATA=>IDE spare adapter I have. XP installed fine and the RAID/SATA controller is recognized by Windows (and the driver reports no errors). I'll try connecting something to the SATA ports to see if they work within Windows, if so, then the only issue is the bootrom (and I'll try reflashing the BIOS). Interestingly enough, no power issues. I have 1 HDD, 1 floppy drive, 1 DVD reader, the MX440 and one PCI WiFi adapter, and it seems to be rock solid. Sure, thanks to the SATA=>IDE adapter the HDD seems to be a bit slow, and the MX440 doesn't seem very snappy at Full HD, but overall this has been a moderate success.

Final update: IT LIVES!

I did EVERYTHING, I even modded my BIOS and injected a newer bootrom for the VT8237r... then I had the idea to use a samsung utility to set the driver to SATA150. Didn't have a lot of hope because I already tried using the jumper (this board has trouble detecting SATA300 drives). I noticed that ES-Tool detected the RAID controller and used it directly, so I decided to try connecting the HD to the SATA port, and see if ES-Tool would detect it.... As soon as I did it and started the PC, didn't even get to ES-Tool: THE RAID OPTION ROM APPEARED ON SCREEN!!!!!!!! I suppose the HDD ignored the jumper settings...

Now everything is running as it should. I've got 2 PCI boards here and my 6600 back, and no "not enough power" message. Whatever caused it, it went away as I washed the board 😀