Currently it's at 450 and very stable, with 2.0v at temperature reaching as high as 38C.

However, when I turn it up to 500 (83mhz fsb) system freezes in Win98 within 5 minutes. I've tried voltages from 2.0, 2.05, 2.1, 2.2, all with same result. My AGP is turn down to 2/3. And temperature never reached higher than 34C and it freezes. The weird thing is it boots into win98 fine. I can use it for about 5 mins and then freezes. Temp reading at that time is below 35C.

Can it still be a cooling problem when I can hit 450 at a higher temperature? I read in another post that HD might be a cause, how can I check that? Should I burn in the chip at 2.2v for a while even if the system crash just to let it get used to it?

Here's the current specs:

C400 @ 450
bh6 at 2.0v temp monitored between 29C to 38C
128 meg PC100 cas 2 ram
16 meg agp diamond monster fusion
SBLive value
Zoom 56k modem internal
cpu heatsink with dual fan
front and side case fans in Inwin 500a case
WD 10.2g caviar ata66 HD @ 5400 rpm

Any comments or suggestions you may have are wellcomed.

If I can't get it to 500 stable, I'm still quite satisfied at 450. Just wanted to give it a shot.