Pentium M keeps downclocking on Aopen board

[DEViANT]

Has anyone else had this issue? I know it randomly occurs on the Shuttle ST20G5 (which is a completely different breed I know) but it's happening on mine too. I have an Aopen EY855 (same board as EZ855) system with a Pentium M 1.7Ghz Dothan in it. I clocked it to 1.90Ghz @ 112FSB and it was stable because when I got it with a 1.01 BIOS it wouldn't go to 133FSB even though the chip would. Now with the release of 1.03 and 1.03a (beta) it has a 'H/W switch' they say which allows 133FSB and now it can boot at that rate giving me a rather nice 2.26Ghz CPU - after a lot of fiddling with the options because the RAM runs at DDR443 at this speed and despite having DDR500 RAM (Corsair XMS4000) the timings can't be set looser than 2.5-3-3-7 so it BSODs on boot.

Anyway my point? The machine just sets the FSB back to 100Mhz occasionally, even during a warm restart, maybe even during operation. I might go back to 1.03 non-beta release and see if that fixes it, but might suffer the over-tight RAM settings...

Any ideas or help of any kind is appreciated or I'll be resigned to running at 1.9Ghz again! Thanks.

[cadlon]

I gotta MZ855-II same MB

I'm running the 1.3 BIOS and a 735 Dothan (17x100 default 150x15 OC) and occasionally, when "tweekeing" the FSB it'll boot @ 15x100 when i reboot after all is back to what i set in the BIOS.
I've never had i clock back once im up and running though

I did find the machine wasnt quite as overclockable with the 1.3a BIOS.

Bear in mind the VDIMM voltage is not adjustable and set to 2.5v, most OCing RAM needs at least 2.7v to get going.

out of interest what RAM are you using? i opted for Crucial Ballistix PC3200 which i can run at DDR400 2-2-2-5 @2.5v plus a little bit faster when doing a SuperPI run

[DEViANT]

Sorry, would have replied earlier if the topic subscription actually worked properly...

Mine is now booting fine (touch wood) at expected speed of 2.26Ghz (133 x 17), default would be 1.7Ghz (100 x 17). I am still forced to use the memory divider to get the timing acceptible on my RAM - which since you asked is Corsair XMS4000 (I think it's 3-4-4-8 @ DDR500). It's good RAM but at that DDR443 speed the machine requires it to run at 2.5-3-3-7 which it can't do and so it fails. That said I might up the divider and see if I can get it to run ok with more voltage.

On that note, I wonder if Aopen will release a BIOS with more voltage tweaking options - I bet I can get my CPU higher than 2.26Ghz with more voltage - not that I've tried, 133FSB is quite a nice rest point.

[cadlon]

I have some major problems with the onboard sound & USB i.e. they don't work when over clocking

i've had the CPU upto 168 x 14 (2.3~GHz) it'll run SuperPi ok, but no sound
it seems to hit a wall just befor 2.4GHz and doesnt want to go any further