P4P800 Deluxe + 1.6a = interesting problem

[cursor]

I got ahold of a newegg refurb P4P800 deluxe last night and put my old 1.6a onto it and came up with some interesting results. Before I was shaky at 150 fsb on my P4S533, but now I can go up to 166 stable in prime 95 with PAT enabled. Temps get up pretty high (58 C under load).

Anyhow, if I go up even 1 mhz over 166, I can't POST. What's up with THAT? My vcore is 1.75, AGP at default (1.5v) and memory is at 2.75v. I don't know why I would go from rock solid to no POST in 1 mhz... :bang head

I've tried setting my memory on 266 and 333 with loose timings. I've settled on 2.5-3-3-6 at 333. With all the memory stuff I've tried, I don't think my limitation is my RAM. (but I DO have some PC4000/DDR500 on the way). [I know I'll need to get a 2.4C to get the most out of that RAM by the way]

PC probe shows pretty good results with everything BUT my PS 12v rail hits 11.612v under load. :( I'm pushing too much hardware on my 350 Fortron. I'll have to replace that soon... New Antec, 430 most likely.

Anyhow, here's the big question:

What can I do to break 166 fsb?

[Lancelot]

You already have a 1Ghz OC right now which is what most northwood CPU's tend to shell out at maximum if you're lucky. (and you're lucky!) What you are running into now is called 'the brick wall' most i865/875 chipset users are running into eventually. Your chipset can do 200FSB default but your CPU isn't upto it appearantly. Going from 100 to 166FSB is a great OC though, and now you even have PAT and Dual Channel!

[cursor]

Here's a little update. I got some weird errors after about 2 hours on Prime95, so I backed down to 165 fsb (2640 mhz), and ran Prime all night. My temps got pretty high, though. Average was 59c with (short term) dips and spikes at 58C and 61C :eek:.

I'm now messing with the voltage to try to avoid Sudden Northwood Death Syndrome. It would POST, but not load windows when I tried running 1.6v, so I am running 1.7v now.

Memory is at 2.5-3-3-6-4. I don't exactly understand how Asus does the memory divider jobber, though. There are 2 manual settings for memory: 266 mhz and 333 mhz. I'm set on 333. I assume this is 1:1? Or is it 4:5?

Thanks for the advice Lancelot. I get the idea that I AM reaching the limits of this CPU. Where was this motherboard in April of 2002 when I bought this chip?! :D

[Merc Zephyr]

Good results, Cursor.

I used to have my 1.6a on a p4s533 and then on my p4p800. It would do 2.4ghz at 1.65V on the p4s533 and 2.46ghz at 1.7V on the p4p800.

Anyhow, if I go up even 1 mhz over 166, I can't POST.
Did you update the bios? I seem to remember something about a "hole" from 166 to 199mhz prior to I cannot remember which bios (might have been 1006 but I'm not sure). So your chip may yet do more than 166 but your voltage is already high.

Cheers