I am running a PIII 866 (Slot-1) on an Abit BE6-II motherboard, and have been doing so for over a year. Recently, I began experiencing problems with stability, the system rebooting itself randomly, most frequently during the XP splash screen. When I changed the BIOS settings to lower CPU (and FSB) speed, everything returned to normal. Any ideas as to what the problem is? Is my CPU shot, or have some other components suddenly become incompatible with the 133 MHz FSB?

Rebooting is normally caused by either overheating, a power supply problem, or bad memory. Since slowing down the CPU solves the problem, bad memory can probably be ruled out as a possible cause.

First, make sure all fans are running, there are no cables and wires in the path of any fan's air flow, the computer's vents are unobstructed(incl. the power supply's vents), the computer is not near a heat source, there are no electric motors on the same circuit(air conditioner, etc.), there is no dust build up inside the computer or on any fan blade surfaces, etc.

Next, check the heat transfer compound between the CPU and its heat sink. Over time this compound will sometimes ooze out between these surfaces, reduce the heat sink's efficiency, and cause the CPU to overheat. Use Arctic Silver 3 as a replacement. It is formulated to prevent oozing out.

If the problem persists, then suspect the power supply module.

With ski on this one, since slowing it down keeps it running the I think heat is your major issue.....

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mjc
Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

Adding to Ski's shopping list

Make sure there are no open expansion slot holes in back of PC - this can interfere with air flow also - like opening a car window with A/C running -

And just to get on the wild side - these can be symptoms of overclocking - happens when a counterfeiter deliberately mislables a cpu knowing it will run overclocked - It happens



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Old dogs CAN learn new tricks

Thanks, all.

The processor is genuine enough - I have the fancy sticker and warranty leaflet to prove it. While running the processor at 650/100 proved more stable, adding another hard drive made things worse again. I still experience the occasional sudden reboot, and this morning I had to disable the CD burner as well to get it to boot properly. The heat sink and CPU fan has been cleaned, and there does not seem to be any 'oozing'. Is this a power supply problem, or could it be a weakness in the motherboard?

It could be heat but after your last post where you are implying that adding devices make it worse and disabling makes it better it sounds like your PSU is not pushing out the correct voltage or you have installed additional devices and the PSU cannot push out enough power
http://www.PCGuide.com/ubb/smile.gif

Right. The 235W Power Supply has been scrapped, and a new, silent 350W one is now in place. However, Windows XP still resets itself, most often during the display of the XP Splash screen, but also at random points after the boot sequence is completed. To achieve complete stability, I have had to clock the CPU down to 433 MHz. Still, I have encountered similar problems when using my old PII-300, so I guess that only leaves the motherboard as possible culprit...Any thoughts?

If you can get into XP, look at the logs, they may give you a little more info.

What was running on thixs machine when it ran without problems?


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mjc
Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.


Please Post Questions in the forums, not my email. Thanks

Well, I have consulted the event viewer, and found that the following error has occured frequently over the last weeks:

"AMLI: ACPI BIOS is attempting to read from an illegal IO port address (0x71), which lies in the 0x70 - 0x71 protected address range. This could lead to system instability. Please contact your system vendor for technical assistance."

Windows Help Center didn't provide much information on the subject, any ideas what this means? Could this be the source of the problems? I upgraded the BIOS a couple of weeks ago, long after the random reboots and crashes first started occuring, so it doesn't seem to have made a difference either way.

This behavior can occur if your computer's basic input/output system (BIOS) attempts to write to a port in AML [Advanced Configuration and Power Interface (ACPI) Machine Language]. This attempt causes Microsoft Windows XP to prevent any access to that port. This feature has been designed to improve the stability of your computer's operating system.

This behavior is by design. Contact the BIOS vendor for a possible BIOS update. For more information see:
http://www.microsoft.com/hwdev/tech/onnow/BIOSAML.asp

Okay...

I've now had the opportunity to observe patterns in my computer's erratic behaviour over time, and it seems that clock speed is the main issue here. At 133 MHz, it will crash almost constantly. At 100 MHz, it proves a lot more stable, but still crashes on a daily basis, sometimes more frequently. At 66 MHz, it works perfectly, albeit with the total speed halved due to the multiplier being fixed. When swapping the CPU for an old PII-300, I get exactly the same problems when running it on 100 MHz as I do with the PIII. Someone suggested it might be the AGP video card, as similar problems have apparently occured with other similar cards after a couple of years. Anyone heard of similar cases?

The ACPI error message seems to be a dead end - as I understand it, this is just a minor issue that XP has with the BIOS (Feel free to correct me if I'm wrong - the Microsoft Support site didn't shed very much light on the subject). The instability started suddenly (initially, part of the problem was that the computer often wouldn't boot at all, but this now seems corrected by the new PSU), without any new hardware or software having been added for weeks. The CPU looks just fine, and as I wrote earlier in this thread, running a PII on 3x100 MHz seemed to cause just as much instability as a PIII at 6,5x100 MHz (the multiplier is fixed).