Need help with upgrade to AthlonXP 2400+(Thoroughbred)

[johnorun]

HELP

I can't get my Gigabyte GA-7VAXP M-board based PC to start, since I tried installing a new AthlonXP 2400+Thoroughbred to replace my current AthlonXP 2000+ CPU.
It's my main computer at work and I'm f@@ked if I can't get it back online by Monday!

Here are the steps I took:
First, I unplugged the PC
Second, I unplugged and removed the heatsink/fan and then removed the old CPU from the socket.
Third, I inserted the new AthlonXP 2400 in the socket.
Fourth, I plugged in the PC and switched it on for a brief bench test to see if the new chip would be recognized.
Grrr....the fans went on and after 2 seconds the PC shuts itself off--that's it!
Next, I retried starting it up several times with the old CPU, but it still shuts off after about 2 seconds...what am I missing here?

I think it's probably something simple that I overlooked, but I'm stumped.
Someone PLEASE tell me some things to try. I need to get back in business on Monday AM....

Thanks.

[Neon]

I don't know that specific board, but here's some general things to try:

recheck that the heatsink is properly seated, and the fan is plugged in.

You mentioned a bench test. does that mean you removed the motherboard from the case? If so, recheck that it is properly isolated from ground, either on a nonconductive surface outside the case, or else mounted on standoffs in the case. Make sure there are no loose screws touching the back of the board.

Try resetting the CMOS.

[johnorun]

[smithy]

I wouldn't try to start it up without a heatsink attached. That board has a thermal shutdown function, which I guess shuts down the board if over temperature is detected (which would be the case if you boot it up without a heatsink attached). I would put your heatsink on and give it a try. I'd give it a go with the heatsink/fan installed first up and see what happens. I reckon this is what caused it to shut down.
Otherwise remove the battery from the motherboard, leave it a couple of minutes, reinstall it and the settings should go back to factory defaults.

[Qwerty]

The $%&#! thermal shutdown function isn't worth it's name. It reacts too slow and the measurement is too inaccurate.
I managed to destroy an Athlon XP 2000+ with a heatsink attached! The thermal protection was set to shut down the PC if the CPU temperature reaches 55°C, but it didn't help to prevent the destruction of the chip. I wanted to test the CPU and started Prime95. The thermal protection was not able to shut off the PC in time.


Here are some suggestions from me

- Have you plugged all the power cables back in their sockets?

- Have you plugged the cable of the CPU fan into its own socket? Its extremely important to plug this cable into a proper socket (called "CPU", "CPU Fan" or "CPU Fan 1"). If you plug the CPU fan in another socket (ex. "chasis fan" or something like it) it will work, but the motherboard will think that the CPU fan is not rotating and will shut down the system after a couple of seconds.

- Is the power cable of your video card plugged correctly? Is the card fully plugged into the AGP / PCI-E slot ?

- Another possible cause of the problem is a short circuit. It can occur if you plug a power cable wrong. Especially the small power plugs for floppy or video cards can be plugged incorrectly with force.

[Neon]

with K7 cpus, never run without a heatsink + fan. The risk of destroying the cpu is too high. There is rapid intense localized heat buildup on the chip die at startup. If running without a heatsink, the thermal protection shutoff on the board cannot detect the heat and react quickly enough to shut down the system.

Most late model boards will not start if the cpu fan is not detected, so that fan must be plugged in to the proper cpu fan header.

The BIOS does not get erased when the cpu is upgraded. A BIOS flash utility is required to change the programming, so that does not change.

The BIOS data is held in CMOS, as long as the battery is good. You can reset the BIOS to default by either moving the appropriate jumper to reset, or by removing the CMOS battery.

For now, hold off on resetting BIOS. It isn't likely the problem. It seems more likely a power problem, so make sure cpu heatsink is mounted properly (it only goes one way), the fan is plugged in, recheck cables are plugged in properly.

[Cobracon]

I haven't read any mention of heatsink compound. The quality and quantity are very important.

[johnorun]

Thanks for all the helpful hints.

The new chip never had a chance to even get warm because the power went off after about two seconds every time I tried to start up.
I didn't disconnect any other parts of the PC except for the main power cord and heatsink fan.

I did have the heat fan plugged in correctly one of the times I tried to start the PC, but it still shut down ! It wasn't clamped on the CPU though.

BTW, there is a heat sensor that was taped to the bottom of the old chip. Would it have a way of telling the PC to shut down?

I'll try clamping the heatsink on the new chip and see if it starts up on Monday.
ohhh, I hope it works,,,,,

[johnorun]

Hmm..well it's Tuesday and I'm still stumped with this problem.

I have installed the new Athlon XP 2600 with heatsink and thermal paste.
I have a keyboard and monitor attached also, but when I press the ON button, the fans run but the power shuts down after 2 seconds with no beeps or chance to enter the Bios setup.

I wonder if I need to change the settings on the motherboard "CPU speed/clock ratio" switch or the "system bus frequency" switch?

The Clock ratio is currently set to AUTO (the ratios range from 5X to >+12.5x) and the bus frequency switch is set to 133Mhz (The 3 choices are 100, 133, or 166Mhz).

I looked up the Athlon xp 2600 chip settings on CPU-world and the clock ratio multiplier is 15 and the bus speed is 266.

Any other ideas??

Any help appreciated.

[Neon]

What motherboard are you using? Does it have manual switches / jumpers for CPU clock ratio and bus frequency? If it is that old, then the BIOS probably does not recognize later model Athlon XPs, and the board might not support them.

For AXDA2600DKV3C, the proper multiplier is 16, not 15. Are you certain you have the 3C model? It is the least common 2600+, there are more 3D and 4D models.

[johnorun]

[Neon]

Ah, OK - 15 x 133 MHz is correct then.

I was going to suggest that you might need a BIOS update to support the 2400+, but you said that the same symptoms occur now with the older 2000+, so probably not. Also, a Via KT400 board should be new enough to recognize 2400+ at release.

The symptoms are certainly reminiscent of a power plug somewhere plugged in the wrong way. You could double check that, or try another power supply.

By the way, if it is one of those little flat heat sensors, that should make no difference to the startup.