Did the KB led's flash briefly when first powered ? Have you tried a speaker to see if it beeps or screams, just in case the POST card has a compatibility issue with that board ?
other than those I got nothing.

My SiS501 board doesn't boot if SIMMs are only installed in the second bank (top two slots on my board, just like you have them inserted).

Also the chipset doesn't support 32MB SIMMs you mentioned. 16M is the max you can use as there are only 12bit raw/column signals

Horun wrote on 2020-02-09, 16:21:

Did the KB led's flash briefly when first powered ? Have you tried a speaker to see if it beeps or screams, just in case the POST card has a compatibility issue with that board ?
other than those I got nothing.

Not a peep from the speaker. The LEDs flash very briefly immediately at power-on.

Strongly doubt a compatibility issue with the POST-card, as I have two and both work fine on the P5SP4.

mpe wrote on 2020-02-09, 16:25:

My SiS501 board doesn't boot if SIMMs are only installed in the second bank (top two slots on my board, just like you have them inserted).

On the Asus P54SP4 and P5SP4 the top two are bank 0. It works on the P5SP4 with the SIMMs in bank 0. To be sure I also tried bank 1 on the P54SP4, but same result as with bank 0.

Also the chipset doesn't support 32MB SIMMs you mentioned. 16M is the max you can use as there are only 12bit raw/column signals

Oh? As I said, these SIMMs came from my P5SP4, with the exact same chipset, where they happily give me 64MB total. They are double-sided 32MB modules, so each chip is only 16Mb (4Mx4).

If double-sided it should be OK. I mixed bits and bytes

How about bad a BIOS chip or flashed with wrong bios image ?

Horun wrote on 2020-02-09, 17:32:

How about bad a BIOS chip or flashed with wrong bios image ?

Flashed a second EEPROM with the latest image from the Asus site. No change.

This board still has some tantalums on it. Check them, they like to fail/short without being visible or they go out with a loud bang.

Nvm1 wrote on 2020-02-09, 19:12:

This board still has some tantalums on it. Check them, they like to fail/short without being visible or they go out with a loud bang.

No really loud bangs and did a visual check too...

Good idea though, I'll check for resistance over their points (not perfect when in situ, but should show difference between short and workgin)

I am troubleshooting a Socket 5 board with the exact same symptoms, only it's a Neptune (430NX) based board (FIC PN-2000). I also tried flashing the latest BIOS on another chip, several known good PCI/ISA VGAs, CPUs, PSUs and FPM memory sticks but no dice. Voltages are fine but POST card doesn't budge from '-- --'. The former owner claims it was working just days before he removed it and gave it to me, but since I got it for free I have no reason to doubt him.

It also has a soldered DS12887 block (they really did like these things during the mid-90's!), so as a last resort I decided to desolder it with my cheap ZD-915 gun, knowing these things sometimes prevent boards from booting. Luckily it came out very cleanly. Once I get DIP24 sockets I will solder them in and test again with a known working (and CR2032-modded) DS12887. If it works it may also be worth for you to desolder it.

The Dallas shouldn't have created this. With a dead battery start the board should still start and display an error. Even with failed Dallas (or no Dallas at all) the POST card should display at least something as it should fail half way in the POST (although the board wouldn't be displaying anything).

But everything is possible.

Everything is certainly possible, but it would be a first for a DS128(8)7 not to boot at all. From PS/2 model 30 to Asus P55T2P4, boards with those beasts just get offended at lack of settings. It's the DS1387 RealtimeRAMified boards that sometimes utterly refuse to do anything if the battery is dead.

Checked the caps - can't be totally sure that they are still doing their capacitive job properly in-situ, but none are completely shorted. Scratch that one...

Am now wondering about clock signals. Unfortunately I don't have an oscilloscope to check them 🙁

Does your POST card have a "Reset" led? Does it turn off shortly after you apply power?
Do you have means to measure the clocks on the board (ISA, PCI, CPU, KBC)? - edit: typed that while you were typing 😀
Try powering up your board while applying some pressure with your thumb to each big chip, if this changes anything then you have bad/cracked solder joint(s).

I purchased two of these boards myself..

What could help is remove DIP chips from there socket and put some IPA 99,9 procent in it with a cotton stick. And also trying to clean the legs of the chips.
Sometimes the connections of these chips are getting very bad of corrosion..

Also put IPA on the flat pack chips en try to clean them.

Did you also tried the third and the fourth memory bank?

The latest bios is 0204..

Use the attachments on your own risk.

The board also dont work maybe because of a bad memory bank which is damaged.

As last option is maybe to reflow the solder joints. Maybe it give you some light in the darkness.

Just restored a system with one of these motherboards in it, glad to say it POSTs but BIOS reporting CMOS battery fail. But i'll be damned if I can find the battery!

breno785au wrote on 2020-02-23, 12:08:

Just restored a system with one of these motherboards in it, glad to say it POSTs but BIOS reporting CMOS battery fail. But i'll be damned if I can find the battery!

The battery is inside the Dallas RTC module in the bottom right corner. You can replace the module or hack an external battery to it. Googling "Dallas RTC bettety hack" should give you plenty instructions. Have fun! 😃

Doornkaat wrote on 2020-02-23, 19:34:

breno785au wrote on 2020-02-23, 12:08:

Just restored a system with one of these motherboards in it, glad to say it POSTs but BIOS reporting CMOS battery fail. But i'll be damned if I can find the battery!

The battery is inside the Dallas RTC module in the bottom right corner. You can replace the module or hack an external battery to it. Googling "Dallas RTC bettety hack" should give you plenty instructions. Have fun! 😃

I thought it might be something like that, thanks for letting me know!

Robin4 wrote on 2020-02-10, 00:48:

I purchased two of these boards myself.. […]
Show full quote

I purchased two of these boards myself..

What could help is remove DIP chips from there socket and put some IPA 99,9 procent in it with a cotton stick. And also trying to clean the legs of the chips.
Sometimes the connections of these chips are getting very bad of corrosion..

Also put IPA on the flat pack chips en try to clean them.

Hopefully will have time to try this later this week.

Did you also tried the third and the fourth memory bank?

There are no third and fourth bank - this is a Pentium board so two SIMMs = one bank. The bottom two are bank zero, the top two are bank one. Tried both. No change.

The latest bios is 0204..

In my OP I mixed up the numbers of th P5SP4 and P54SP4 BIOS versions (I have both, the P5SP4 works fine). I'll correct OP and try yout 0204 image just to be certain.

Use the attachments on your own risk.

Not much risk with an EEPROM flasher 😉

The board also dont work maybe because of a bad memory bank which is damaged.

Possibly, but as I've tried both banks (with known-good SIMMs that work on the P5SP4) they would both have to be damaged. No sign of damage to the traces around the SIMM slots.

As last option is maybe to reflow the solder joints. Maybe it give you some light in the darkness.

Would like to have an idea exactly which chip(s) need this before I do that, but lacking an oscilloscope I can't get much further than checking continuity between GND and 5V lines at pins, which shows good everywhere I've done so far.

This sounds like a stupid question but I wouldn't have to configure any of the drives in the BIOS for this motherboard right? Motherboard isn't detecting any IDE drives, have confirmed they work in another system...

Usually you have to set the parameters in the BIOS. Via auto-detect feature or set to AUTO in the Standard options.