overclocking a P3 Coppermine

deadduck

i was wondering if it's safe to overclock a P3 600MHz to 700MHz without installing any extra heatsink, fans etc. my mobo is limited to P3 700MHz so there's no point in getting a new cpu. the options are in my bios so it'll be easy enough

po0k

I've a Slot1 800Mhz Cu 100Mhz FSb.

Afaik there's no way to upwardsly adjust the multiplier, so you're left to resorting to FSB adjustments.

My mobo is an Aopen AX6BC, and support quite high FSB setting s(153Mhz last time I checked) but it doesn't have the multipliers for the AGP and PCi bus on the board for anythign but 100Mhz and 66Mzh (2/3, 1/3 and 1/1, 1/2 respectivley).
Depending on your ram and you board...and probbaly the stepping of you cpu (odd steppings seem to be better for overclocking), you will see differing ceilings for performance.

deadduck

the multiplier options aren't available, just the fsb. the mult. seems to be set at 4.5 and the fsb is 133.

deadduck

i set the fsb to 150 (cos its the max setting), so 4.5 * 150 should = 675 and i'm getting 671. i reckon this'll be safe, someone let me know if i'm wrong

po0k

get some cpu, memory and bus intensive apps - mprime, SiSoft Samba burn-in tests, or google for similar apps with "burn-in utility"

Only way to check is to run the bitch into the gronud for a day or so non-stop and see if she pulls through.

You;re PCI and AGP clocks will probably be a bit out of whack now too, AGP running at 75Mhz I'd say and PCi at 37Mhz. no terribly out-of sync, but it's still eough for some cards (particularly creative sound cards I've heard) to get touchy. Try it and see. You won't do any major damage, and tbh, even if you do it's a good reason to get a new machine
you could spend €300 and get a very good core system now (mobo, cpu, ram and case+psu)

Gerry

deadduck, if you can tell us what motherboard you are using, that would be a great help. Your manual says 700mhz because that was the fastest chip available at the time. It can take all chips which run at 100mhz fsb, which includes a p3 850 ( there is a p3 1ghz with 100fsb, but its useless ). Its able to take 133mhz chips, as your cpu is on a 133mhz bus. Its unfortunate, because you won't be able to overclock it very far.
What Syxpak is referring to is the pci speed. Normally this is supposed to be 33mhz. On a 100mhz fsb, a 1/3 divider is used to get 100/3 = 33.33.
The bx chipset supports a 1/4 divider also, an undocumented feature, but one which needs the mobo manufacturer to bother implementing it. And so a lot of the older bx boards dont have it. Which means your pci bus would be running at 44mhz at 133mhz. Not a lot of cards can handle that, perhaps 3com and intel network cards.
I doubt your machine is a bx though, unless it was built by an overclocking enthusiast.
So check out what the board is, and let us know.

deadduck

the mobo is made by TYAN, its a Trinity 400

deadduck

also, just noticed that the manual states that the multipliers are on the mobo and can be pushed up as far as 8. this means at max. i can have it going at 1200MHz. i know this would never work, but what do you think would be the most i could push it and what kind of cooling should i have

po0k

"How long is a piece of string?"


Here's what you do.
Go into the BIOS, raise the FSB a few Mhz (not too much of a jump), reboot, run some cpu/memory/FSB intensive apps for a few hours.
See what happens.
if all's good, repeat with another small increment of FSB.
You should also keep testing PCI and AGP devices such as sound cards, network cards and graphics cards to ensure overall stability.
If the system becomes unstable during a memory/FSB test you could try setting the memory timings to less aggressive settings, it'll make bog-all real-world difference to a machine such as this, but could be the difference between running a stable rig or a piece of rickety silicon.