P4 3.0 Chip Limitation?

[vette 406]

P4c800Dlx
Corsair 2x512 3500C2 mem
ATI 8500DV
Timings 2-3-3-7-8
Temp 33C @ idle; 47C @ load
CPU Pent. 4 3.0GHz
DDR Voltage @ 2.85
CPU Volts set to auto

The Corsair mem. is 434 MHz (217 freq) which yeilds me 3255 GHz. My problem is that I cannot go one more click up without freezing my system while rendering a movie. According to my FPO/Batch # this chip can go comfortably to 3.5GHz, I have tried many variations in voltage and timings as well as 5:4 ratios. I am able to post at the higher speeds (218-220) but after about 10 to 15 minutes of video rendering my system will freeze solid requiring me to shut down the system.
Does anyone have a solution to this problem, or, is my chip just at its max speed of 3255GHz.
Any suggestions will be sincerely appreciated.

[ComPooTer]

must be heat, are you running with the stock heatsink/fan? high temps prolly

[vette 406]

Yes, I also have a two fan power supply and a 120mm case fan.
I bought a fan for the Northbridge but haven't attached it yet. Although it never feels hot-to-touch when I have the side door off.
When rendering a movie I do periodicly check the temp with "Asus Probe", I have yet to see it exceed 51C.

[causticVapor]

Check the northbridge thermal interface, and also elevate the CPU voltage.

Believe it or not, Northbridges are often the limiting factor in P4C overclocks. Most P4 D-steps top out at ~3600MHz in the Core, anyways.

[vette 406]

How do I check the thermal interface of the Northbridge?
If I up my voltage to 1.6500 I think I can stay under 55C

[cheekymonkey]

change the voltage on the cpu manually and increase it in small steps to see if the system becomes stable.

If I'm o/c a chip I always use manual settings, Auto is too conservative.

[vette 406]

I just installed a Chipset Fan, I increased my freq. to 218 from 217 and it appears to be stable with voltage @ 1.625 and timings @ 2-3-3-7-8.
I tried 219 last night but it blew-up on me after an hour of rendering a movie.