First post, by flynth
I have an acorp 6via86 rev 1.4 motherboard with bios version 2b. According to the manual it should support cpus up to 833mhz(including coppermine p3 in socket 370), but I can only get it to work with p2 350mhz.
I have 3 slot1 cpus. A Celeron 266/66, a p2 350/100 and a slotket card 370sp rev 2.0 mounted p3 866/133. It seems only the p2 works in the motherboard. I made sure jumpers are set correctly, but this motherboard has no fsb selection. It auto detects it. It is specified for 100mhz max fsb, but the BIOS has options to set up to 133 and the user manual seems to suggest it should still work with 133 with compatible components. Unfortunately I couldn't get it to work with the old Celeron and the newer p3.
First let me talk about the motherboard itself. Its color is yellow and the writing on it says 6bx/via/zx rev 1.7. But the south bridge is made by via so I think it is an acorp 6via86. There is also 6via86p that fully supports 133fsb, but it's bios post string is different.
Now, few versions of bios exist for this motherboard. My board had version 2A. I tried upgrading it to latest (2D), but the board doesn't work at all even with p2 350 after the upgrade. Having tested all 4 bioses the latest one that works is 2B (perhaps it is 6via86p that someone flashed wrong bios for? There is a glued on radiator on the chipset so I can't really check).
So this is the first weird thing. That it boots only with one of my cpus. The slotket has ability to override fsb to 100mhz and voltages from 1.8v to 3.5. I left voltages on auto detect, but I did try fsb override with no effect. I measured the voltage when p3 is inserted to be slightly below 2v (unfortunately my meter is not very precise). So this sounds about right as the cpu needs 1.7. (the motherboard should be able to go down to 1.5v).
I tried various pc133 sticks of ram with no difference. I tried various multiplier settings. Interestingly it is not possible to downclock the p2 350 (perhaps the multiplier is locked). If the wrong one is set it refuses to boot. Also my p3 866 requires a multiplier of 6.5 while the manual lists the highest one as 6. Perhaps that's why it fails to boot?
When it fails to boot there is not even a beep.
I have recently received a post diagnostic card so maybe it will help me in troubleshooting it.
Should I try flashing a bios for 6via86p? (I have a programmer). Does anyone have any other ideas? How do "unlocked multiplier" p3's work? Does one need to get a specific model of a cpu, or are they moded somehow? If I had an unlocked multiplier perhaps it would boot at 6x.
Then, I find it very weird it only boots with two versions of the BIOS. Why would it work with version 2b and not 2c and 2d?
I hope someone can shed some light on those questions 😀
Also I include a photo of a sticker on the MB, perhaps someone recognises those numbers and can say for sure if this is 6via86 or 6via86p?
Yes, I had to cut the cpu's radiator to make it not obstruct the agp slot...