P3 Overclocking problems... Help please!

[sozugk]

Hi,

I have an Abit VP6 borard with 2 P3 800EB's. Before I purchased a Corsair PC150 512MB Ram couple days ago, both CPUs were able to go up to 950MHz but when used together I could not get passed 858MHz. People I spoke to recommended me to buy Corsiar and it would solve my problems. Well I waited for a while and recently purchased it. Not both CPUs go passed 1gig up to 1020 (170fsb) which showed me RAM works. HOWEVER, when I used both of them I still cannot get passed 858MHz. It is driving me nuts. I took all the PCI cards off only with geforce2 MX400 64mb on and did not help. Now I have the best overclocking RAM, 2 CPUs that can overclock passed 1gig, a fairly good video card but I still cannot get passed 858 which is 143fsb. I cannot seem to figure out where the problem is coming from. Can someone help me out please? Thanks.

[engjohn]

It is not uncommon for 2 good OC'ing CPU's to not over clock as well in a dual configuration. Just remember you have twice as much to go wrong.

Are the two CPU EXACTALLY MATCHED.
Really close serial numbers, same batch, same stepping??? All of this makes a difference.

[DAppel]

Don't forget that now you have TWO CPU's draining current from the mobo.
If they were powered in series the voltage would be cut in half. That's not practical. So they are powered in paralel, but that cuts amparage in half.

The manufacturer sure did place a few more capacitors and voltage regulators on the board, but the overall current that the CPU's demand can still be too high.

So you can get some ideas from this :
- Change your PSU;
- Cool beter your CPU's, so you can try to lower voltage;
- If you manage to boot to the OS, try running Halt instructions ( CPUIdle, Waterfall,... if you use Linux you don't need to worry, it allready does that by default.) so the CPU's demand less power. Doesn't work on high loads tho.


I know it's a rather simplistic explanation, but I beleive it's correct. Anyone thinks it doesn't apply, please feel free to correct me ... ;)

[outhouse]

generaly the chipset is the weakest link in a duel setup which keeps you from getting a good overclock using two CPU's but the above post sounds good to me, you may try adding a nice sized HSF to your northbridge but i would not expect miracles.