It's odd to see Cx code so soon in the boot process - I assume it's AWARD BIOS? I haven't done much with these lately so my memory of it might be hazy. Did you try to reset the mobo via reset switch after it has been powered? Could be another case of bad power good signal.

Deunan wrote on 2024-05-25, 17:03:

It's odd to see Cx code so soon in the boot process - I assume it's AWARD BIOS? I haven't done much with these lately so my memory of it might be hazy. Did you try to reset the mobo via reset switch after it has been powered? Could be another case of bad power good signal.

Yes, reset does not help. Forgot to mention, PSU is also known good component. 😀

Well, the only thing that comes to mind when I hear that siren is the CPU temp sensor tripping. I looked at some photos on the net and I see this mobo does indeed have such sensor. Is it working properly on yours? I would assume it's just a thermistor, so you can check the resistance and even if it changes if you hold the end of the sensor between your fingers.

Deunan wrote on 2024-05-26, 16:29:

Well, the only thing that comes to mind when I hear that siren is the CPU temp sensor tripping. I looked at some photos on the net and I see this mobo does indeed have such sensor. Is it working properly on yours? I would assume it's just a thermistor, so you can check the resistance and even if it changes if you hold the end of the sensor between your fingers.

Seems to be in working order - 6,6kOhm at room temp, went down to ~5kOhm when i held it between my fingers for some 10 seconds or so.

One looping long "beeeep" is common POST alarm code for RAM problems, but in your case there's a complete "concert" after. I've never heard such a strange sounds from PC-speaker on failed booting motherboard.

I wonder where the thermistor connects. W83977TF doesnt have any analog inputs, there is another chip under BIOS, U2 - can you read its markings?

IT WORKS!

I do not know, why it started to behave differently today, when i started to "play" with it once again.
Immediately, today, i heard that the ambulance alarm is gone. I only got single long beeps. So i continued playing because it was at least some progress after about half a year i've tried to make it work...

And what i found eventually, seems like, that it is pretty picky with memory. At one point i tried 2x64MB ram sticks, and it booted! Then i tried different slots and ram i had and found one 133MHz 256MB stick that works.

It seems to be really cool board! It's a 440BX board that supports 133MHz FSB! The fastest CPU i have to try is S370 Pentium III 866MHz. It works at correct speed. (using slotket)
But there seems to be some kind of instability issue with anything that isn't "era appropriate" Pentium 2 or Celeron. Celeron 300A (even at 450MHz) and Pentium II 450MHz are rock solid. All kinds of Pentium III CPUs so far have had some marginal stability issues. (I have SLOT1 677MHz Pentium 3 and the maximum S370 i have is 866MHz tried so far. I have some more.)

I'm running the rom.by patched variant of BIOS.

As i also have some old Win98 install currently on it, it may be some software issue, though. Have to reinstall OS at some point to confirm.

Thank you for thinking along! And if you have any experience with seemingly unstable operation with this board and Pentium 3 kinds of CPUs, I'm all ears to learn. 😀

Congrats. So, I was right by guessing memory issues. Do you have any explanation about the "concert" part of the sound error codes? Did you changed PSU or some other hardware components in your last successful test?

analog_programmer wrote on 2024-06-02, 09:00:

Congrats. So, I was right by guessing memory issues. Do you have any explanation about the "concert" part of the sound error codes? Did you changed PSU or some other hardware components in your last successful test?

I think i do, but it doesn't help.

On some random events, i got it into this "alarm state". Once was when i tried to set my Celeron 300A to run at 600MHz (133MHz FSB). Another time it was different AGP videocard i tried. Once i think it started to react like it when i tried different RAM sticks.
But you know what i discovered after a while? My ATX extension cable started to become warm! I used the cheapest aliexpress extension cable that i also modified and took molex connections from it, so i have a single 20/24pin connector to connect/disconnect and my whole bench is supplied from it. (The devices on molex connectors don't much matter as i have nothing physcally moving there - ssd and gotek are active)
I did notice that bios reported a little uncomfortably low 12V and 5V lines, but when i checked (from molex connector) with multimeter, everything was okay. When i now discovered warm wires, i checked voltages from the motherboard's atx connector and "lo and behold!", the voltage was very measurably lower! The bios did not lie!

So here's a PSA! The cheapest ATX extension cables from china are using below-standard wire widths! 18AWG should be standard so make sure your extension cable is at least that.

GigAHerZ wrote on 2024-06-03, 18:01:

The cheapest ATX extension cables from china are using below-standard wire widths! 18AWG should be standard so make sure your extension cable is at least that.

That reminds me that I bought a pack of breadboard connection wires and for some reason my contraption didn't work properly. Turns out the circuit pulled some 700mA of current and the wires, which I also used for power delivery, didn't have enough copper in them - so the voltage sagged quite a bit. Same with wires with alligator clips - those were so bad that I ended up throwing them away about 15 minutes after I unpacked them. I got me some much more expensive ones from local parts seller and these are great. And the funny thing is good chances are both were made in China.

Anyway, out of curiosity, did you inspect the wires? There should be markings - if so, does it say 18AWG on them? If you are going to trash this extension then cut the wire in half and make some photos.

Currently testing stability on this machine with Pentium III 866MHz @ 100x6.5 (650MHz) on slotket with looping 3DMark2001 together with Radeon 9250 with 128bit memory bus. So far so good. (I have a 512MB PC133 CL2 RAM stick installed. It's dual-ranked, so the board only addresses 256MB, but that's fine. I have currently no other 133MHz CL2 sticks of RAM right now...)

But no matter how loose i set all kinds of memory timings and other such stuff, i can not make it work at 133MHz FSB stably. It might be caused by the out-of-spec AGP, though. At one point i have to test this machine with PCI graphics card to see, if the board itself is stable at 133MHz FSB.

On another note, there seems to be some kind of issue with Internet Explorer 5.5. When i use it for some 5-15min, then at one point the machine just hangs completely. (I'm using protoweb and oldnet services to get any content on this old machine) It hasn't hanged on anything else (yet!), but with IE, it seems to be a pattern...

Deunan wrote on 2024-06-03, 18:59:

GigAHerZ wrote on 2024-06-03, 18:01:

The cheapest ATX extension cables from china are using below-standard wire widths! 18AWG should be standard so make sure your extension cable is at least that.

Anyway, out of curiosity, did you inspect the wires? There should be markings - if so, does it say 18AWG on them? If you are going to trash this extension then cut the wire in half and make some photos.

The wires themselves claim to be 18AWG. Full line: "1007 VW-1 80°C 300V 18AWG YOUCHUANG - LF". But i have some power cables with markings of 20AWG that feel stronger and thicker inside than this extension cable's wires.

Fake wire is a problem with cheap cables in general. Most of it isn't even copper or CCA. It's some weird alloy that has strangely high resistance (and inconsistent - each conductor in the cable has different resistance while being the same length), is weakly attracted to a magnet, and is the color of old oxidized copper.

So, i've been playing around with this board and seems like there is some kind of issue with it.
I've tried numerous CPUs, RAMs and graphics cards. (I most like Radeon 9250 with 128bit ram - i have 3 of them.)
And there seems to be some kind of issue with any pentium 3 CPU i try with it.

Pentium 2 (3.5x100) and Celeron 300A (4.5x66 & 4.5x100 OC) work perfectly.
One Pentium III i have (5x133) locks up even at 5x100 and other Pentium III on slotket (6.5x133) does the same also even at 6.5x100.
Everything works well until i do something graphically demanding. I can cause the lockup easily with 3DMark2001. Sometimes it takes a bit of time until it locks up, but then it seems to degrade for that day and usually i even can't get passed the first car demo on second+ run.

I'm using Windows 98SE and i've re-installed it countless times. I've also used both SSD with SATA-IDE adapter as well as CF card for storage to have at least 2 different storage mediums tested - no behavior change.
With windows, I've tried all kinds of different orders of installations after windows install. On top of windows, i install 440bx chipset drivers, graphics drivers, soundcard (ymf724) and NIC drivers and all main windows updates. For windows updates i've used windows 98 SP3 (only the "main updates" parts) as well as restored windows updates through browser. The behavior does not change.

I have an oscilloscope, i believe pretty decent one. But I'm very new in this. I tried to measure CPU voltage and 3.3V from graphics card (from an unpopulated capacitor pad) and everywhere i read anything, i see noise/ripple with peak-to-peak of 250-400mV. It seems crazy, especially when considering that my Pentium 3 wants 1.65V. The voltage itself with multimeter seems to be on correct level.
Because oscilloscope is pretty new to me, please instruct me, what to measure and what settings should i have on my oscilloscope to do the measurement. Like AC/DC coupling, the 10x/1x on probe, etc. I don't believe the ripple is that large - the CPU wouldn't be able to work AT ALL with such big noise on its power supply.

So any suggestions and instructions are welcome! It is a beautiful board, i would like to get it fully working.

NB! Not using any ATX extensions for now. All voltages are within normal range measured from the motherboard. I use the latest bios from retroweb, that is patched with rom.by for better support of CPUs and whatnot. For oscilloscope, i used serial port's shield as ground, as it was closest bare and shiny metal. (it should be good ground, right?)

EDIT: Just to confirm.

Celeron 300A @ 450MHz.
128GB SSD over IDE-to-SATA adapter
Fresh windows 98 install.
All drivers + Main updates from Service Pack 3.
DX 8.1 + 3DMark2001

And is rock-solid. I made it to loop 3DMark2001 low-detail cars demo (as that should stress more the CPU, motherboard and RAM instead of being bottlenecked by GPU) and it just continues to loop with no issues.
May there be some kind of incompatibility with P3 type CPUs somewhere/somehow? Not even sure is it incompatibility with the board or with windows or something else... Maybe some of you have encountered similar issues and can suggest some ideas?