Hihg FSB only when hot?

Hi! My problem is that I can go up to 204 FSB, but only when the system has been running for a while (say 1/2 - 1 hour). If I leave 200 FSB and go to bed, next morning the system won't boot. If I put the FSB back to 192 it boots no prob. Then after a while I can go and set it back to 200 or even higher and pass prime, memtest or 3dmark...

I thougth that these things run better when cooler, what's wrong with this one?

You can see my sig to check the components. I know they're a bit out of spec. Any idea why this could be happening?


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Asus A7V333-X
Athlon XP Tbred b 2100
TT Aquarius II watercooling (with home made shroud and duct to exhaust rear fan)
Chieftec case with 6 fans on it
Zalman Fan controler
Enermax 465 PSU (2 fans)
1 512 MB stick PC2700 Kingston Value Ram (Winbond chips) with heatspreaders
2 x 15Gb IBM Deskstar
Leadtek Winfast Geforce 2 MX 400

Dude, how are you able to run 200FSB on a KT333? That puts the PCI bus at 40Mhz! - Props to your hard drive if it can handle that :S - who knows - very odd things can happen at high PCI bus speeds.

Yes, I know . No problems ever with the HD though. Maybe it's because they're a couple of "old" IBM ata66 disks which are not so picky when running out of spec as newer ata100 disks.

I had problems with a Geforce Ti 4200 which wouldn't go stable over 187 FSB. It booted up to 192, but got crashes in 3dmark. My GF 2 MX however never complained.

It is all the time the memory that's holding me back (but I must admit that I'm quite happy with it, taking into acount that is PC2700 with 2.5 cas and now is running perfect 192 cas 2, and once the system is "hot" it goes up to 204 FSB at 2 cas

Things definitely run better when cooler, so it could be another factor that hasn't been considered. Are any/all of your fans temperature controlled?

1st it might be the temperature control fans like someone else here said, what kind of crash do you get when you use 204fsb? BSOD, system shuts down, applications acting weird, static in games?

If you system shuts down a thermal overload sensor might me screwed up.

Another thing it can be is teperature throttling on the cpu. When you boot cold the cpu for example is running at 2ghz and at 40C, within a hour it goes to 70C and throtles 50% to 1 GHZ. You reboot, change fsb to give you 2.5 ghz, mb says it booted at 2.5 ghz but it is doing cpu at 1.25ghz because of the throttling.

No, no temperature controlled fans here. I've got a Zalman fan controller, but it is fully manual. I usually keep them full blast when doing tests, and check the temps all the time (MBM 5) so hopefully that is not an issue. Temps never go over 50 C full load, nor even when I tried my Tbred B 2100 @ 197 x 12.5 (= 2462 MHz) @1.8 volts. I usually keep it @ 1.65 which means full load temps of about 45 C. If I go with asus probe, it never goes avobe 32 C, but that surely is socket temp, not on die.

This is making me nuts ! I could understand it stopping at 192 or 197 FSB and that's it, 'cos is way out of spec, either for chipset (PCI and AGP) and mem, but working over it after some time running is what puzzles me

I still think CPU throttling is being done. I don't know how cpu throtling is done on a athlon platfrom proc, but on my laptop (intel p3 500mhz) when it smartsteps doen the mhz, it doesn't change the multiplier like the k6-2+ but lowers the FSB to 50 mhz from 100 mhz. So if this is being done on the athlon thats why you get more stabile becasue your fsb is being throttled.