First post, by majestyk
The FIC PT-2003 is a nice board. You can add a VRM and run a Pentium MMX 233 with the latest BIOS. It can be equipped with 512K of L2 Cache either asynchronous using DIL SRAM or pipeline burst, when you populate the CELP slot. Since the chipset can address 128MB of RAM (64MB cachable) only, I doubt using 512K L2 cache is useful at all.
But I like the 430FX chipset for nostalgic reasons.
The board came in a quite dirty state. It had some brownish stains on the surface that looked like battery leakage of regular battery cells. I cleaned everything carefully but there still was some corrosion left at the pins of the clock generator and the chips nearby.
When I started testing this PT-2003 it would refuse to POST at any FSB above 50 MHz. It would run fine at 50 MHz, at 60 MHz or 66 MHz it wouldn´t POST or even beep.
I tried with different RAM sticks and CPUs with and without L2 cache to rule out that any component was limiting the maximum FSB.
Then, from time to time all of a sudden it would POST at 60 MHz perfectly, but never at 66 MHz. After a while I suspected this behaviour to be dependant on temperature.
I carefully heated up single components, then cooled them down again to narrow the cause of this issue.
Finally I found that the sentitive component is the Northbridge of the 430FX chipset. When the MCH (SB82437FX66) is heated up at it´s center, the system even POSTs at 66 MHz, but hangs later, when the heat is turned off.
Of course I carefully checked every single pin to make sure the soldering joints are still o.k. , but they are.
I have seen many cases when chips started acting flaky as soon as they reached a certain temperature, but I can't remember any case where a chip worked perfectly only when it´s overheated.
What do you think - can I be sure the MCH is the cuplprit? Are there any alternative explanations for this behaviour?
Replacing this chip is quite time consuming - it would be frustrating to do it without fixing the issue.