It was hard to find any reference to someone having an extremely slow performance problem with this motherboard - I'm guessing that not a lot of people have tried 4GB of RAM with this board plus Fedora Core 7.

The answer for now is to either drop back to 2GB of RAM or just define the mem=3GB or anything less than 4GB in GRUB.

It took days to install fc7 with 4GB or less than an hour with 2GB. Initially I had 2 ddr2-800 2GB dimms which were detected as 667. I then replaced them with 2 ddr2-667 dimms but the performance was just as bad. Removing one resulted in the incredible speedup - but I could also have them both in and define it as < 4GB in GRUB and get the same speedy performance.

Another annoyance with fc7 so far has been that after installing the 100 updates suggested after the install from DVD - on reboot it appeared to hang at starting udev. Selecting a non-xen kernel would let it boot ok.

References online seemed to confirm that it was "hanging" at starting udev. However, I found that if you just leave it alone for long enough it goes ahead and boots. It's a long time plus it says FAILED about halfway through and timed out. But then it boots.

I had selected Gnome as my desktop environment - unsure if it would be different with KDE etc.