Booting problems with ABIT AN7 (post code 9F)

[tortilio]

Hello everybody, I'm pretty new to the forum, and I'm 'desperately' looking for an answer before going definitively mad!!
I also have to confess I'm not so expert about hardware, but I believe I could read and do whatever I might hear!

Well... I'm trying tu run a once working Abit AN7 (Socket A), with a once working AMD Athlon XP 2600+, but whenever I try to turn the system on, it automatically shuts down after a very few seconds (before booting or even loading bios) with the motherboard uttering an alternate sound similar to an emergency siren (although sometimes it not even reaches the time to utter such sound, self shutting down earlier).
The last post codes shown by the motherboard are the following:

9a
98
99 (that's what it shows when it shuts down)
9E (and after a handful of seconds from the shutting down, the 99 turns for a very short while in what appears to be a 9E...)
9F (...than shifting to a permanent 9F)

The story is pretty long, but these are the clue facts: the motherboard once correctly worked with an Athlon XP 3000+, then I tried to put such CPU on a different (previously checked for compatibility) ASRock K7VT4-4X motherboard without success: power correctly reaching the mobo, but no video signal, nor sounds... Therefore I put the CPU back on the Abit AN7, but the system did not work any more (even here no video signal nor motherboard sounds when powering on)!?
I then tried putting on the AN7 another CPU (an Athlon XP 2600+, previously finely used on the ASRock mobo), with it working just a 'little better': the system couldn't work with default bios settings loaded - usually self resetting when updating the DMI pool or earlier - but could go with fail safe configuration, and could correctly load Windows in safe mode. After several hardware and bios tests and attempts, I eventually opted for upgrading the bios to the latest version (719), and everything started working correctly.
At this point (damn myself!!!) I tried to put back on the motherboard its previous CPU (the Athlon Xp 3000+), with it still not working (no video signal). I put the Athlon XP 2600+ having correctly run just a few minutes before back on, and the system started behaving like described at the top!?!

I think I tried about everything: different graphic cards (with some, the system shuts down even more quickly), different RAM blocks (no difference), disconnecting evry drive, disconnecting and then reconnecting the power supply, clearing the CMOS... the CPU and cooling fan are correctly mounted and running... And I currently have no way to make any attempt to downgrade the bios...

Another 'funny' fact is that after unsuccesfully trying the 3000+ CPU on the ASRock mobo, not even the previous 2600+ worked any more on it (though behaving a little more ordinarily: video signal and usual starting beeps, the self power down)!

My questions are: what might ever be wrong? The fact that the system was working with an upgraded bios, before trying to mount the 3000+ CPU makes me suspect it cannot be a matter of hardware... But how to go back??

I feel pretty discouraged and perplexed, and - as a matter of fact - I now have two previously woking systems currently out of order!

Should you need any additional information, just let me know, and please forgive my inexperience with forums, the long post (and moderate experience with hardwrae too...)!

THANX

[Aloke]

There can be various issue behind this problem. I too had a similar motherboard where I was not getting the boot signals. Then a friend suggested me to reset my cmos settings via jumper. You can see two pins near the motherboard battery. You have to check those settings. Once done then I replaced my RAM and then tried. This time my board started working.

[tortilio]

Thanks for the advice Aloke, but unfortunately I already tried messing around the CMOS (both removing the battery, and using the jumper to reset it), without results... I've also tried with different blocks of RAM, still uselessly

tortilio

[Amd Athlon]

I think you need to check it out with the official website of your mother board, if you don't find any solution for your problem then you can also take your board to the technician and ask them to solve this problem which you are getting. If he find some problem with your motherboard then i am sure that you will solve your problem.

[tortilio]

Well, I found out that part of the problem was the absence of thermal paste. I bought some (Nexus TMP-1000 silver), applied it (I think I put a little more than needed), and then the system started up, loading BIOS in fail-safe state, and showing a CPU speed of 1250 (while it's actually a 2500+ AMD Athlon).
Nevertheless, shortly afterwards the siren alarm started again, with the system self shutting down again (although this time its turned on time reached out to the Winodws start up...).
I entered the BIOS setup and gave a look at the CPU temperature (with CPU running at fail safe 1250 Mhz speed) and it was around 70C (=158 Fahrenheit), which appears to be still pretty high.
After trying to load BIOS defaults, and a new self shut down, I looked athe temperature again witnessing a 97C (=206 Farenheit).
An easy conclusion seems to be that my CPU overheats excessively, and extremely quickly. At this point my question would be: do you think I have to look for a new CPU?

[tortilio]

I eventually found out the heatsink being the cause of the problem.
I'm pretty astonished by the facts, but if the previous heatsink (been working efficently for years, and with the fan corrrectly spinning...) had the CPU temperature raising to allarming temperatures in a handful of seconds (with littly shorter times in case of absence of thermal paste), a different one leaves the CPU at an ordinary average temperature of 40 C, without any operating problems.
I find it hard to believe that a piece of metal 'stopped working', and I tried to inspect it: it features a well cleaned (though not with alcohol) copper plate, with a 'natural' slighltly ruled appearance but with no visible scratches or wrappings (the rest of the heatsink being in alluminium). I really don't know what to think about, and how an appareant absence of defects might result in drastically different heating behaviours, but let's say that everything's fine as long as it ends finely...

A BIG thanks to everyone for your help!