Most people leave it at 100, I think thats standard. But like anything else, you can OC it if you wanna. I'd guess the effect is pretty straightforward. It would allow the slot and PCIE bus to communicate with your Vid card faster.
But it can also cause instability. With your 8400, you may wanna leave it at the 100. And no, leaving it at 100 wont do anything bad. (I dont think!) But once you get yer CPU and RAM and such up and being nice, you can try and up the PCIe clock a bit just to see if you can steal an extra 1 or 2 FPS.
Yeah, I forgot to list the RAM, it's 2gb of DDRII-667.
I guess I'll try and lower the PCIE. I think there's a way to 'fix' it. But I didn't, and really still don't, know if it has to stay at 115 because of the FSB overclock.
I'm not using this PC for gaming. It's for an audio workstation, the PC I mix my music on. So, any video needs are minimal. I just happen to have the 8400 lying around. I guess I could use the onboard video if things don't work out.
I think it will be fine. Its prolly the MoBos way of looking like it OCs, hehe! It pretty much looks like the rest of the boards that say they do a speed as an *oc speed. Thats mostly because the board is older and has the old standards. Then they realized that it can run at xxxx and added it as an option, but have to list it as only OC speeds. (because its not officially supported.)
I dont see you runnin' into any real problems as long as you get the newest BIOS for your board. That way it can almost support the new chips!