SE440BX-2?

Big question is whether this is a standard ATX PSU or a Dell-specific one.

Take a look at the ATX connector on the motherboard. If it's in the same position as on this one, then it's regular ATX.

If instead the connector covers the upper pads (right up to the "POWER" legend) and four pads below the connector are empty, it's the Dell pinout. DO NOT connect an ATX PSU to it in that case, as fireworks may ensue.

Assuming it's regular ATX, pretty much any decent modern PSU would work. Even 24p isn't an issue - just connect the 20 pins that do fit and accept that the other 4 will stick out (there's room, they will stick out over the unpopulated pads above the connecotr).

If it's Dell, you need a Dell-specific PSU or an adapter cable.

dionb wrote on 2025-02-03, 15:02:

SE440BX-2? […]
Show full quote

SE440BX-2?

Big question is whether this is a standard ATX PSU or a Dell-specific one.

Take a look at the ATX connector on the motherboard. If it's in the same position as on this one, then it's regular ATX.

If instead the connector covers the upper pads (right up to the "POWER" legend) and four pads below the connector are empty, it's the Dell pinout. DO NOT connect an ATX PSU to it in that case, as fireworks may ensue.

Assuming it's regular ATX, pretty much any decent modern PSU would work. Even 24p isn't an issue - just connect the 20 pins that do fit and accept that the other 4 will stick out (there's room, they will stick out over the unpopulated pads above the connecotr).

If it's Dell, you need a Dell-specific PSU or an adapter cable.

It looks like this one https://theretroweb.com/motherboard/image/sea … 29324502159.jpg

helios98 wrote on 2025-02-03, 15:11:

dionb wrote on 2025-02-03, 15:02:

SE440BX-2? […]
Show full quote

SE440BX-2?

Big question is whether this is a standard ATX PSU or a Dell-specific one.

Take a look at the ATX connector on the motherboard. If it's in the same position as on this one, then it's regular ATX.

If instead the connector covers the upper pads (right up to the "POWER" legend) and four pads below the connector are empty, it's the Dell pinout. DO NOT connect an ATX PSU to it in that case, as fireworks may ensue.

Assuming it's regular ATX, pretty much any decent modern PSU would work. Even 24p isn't an issue - just connect the 20 pins that do fit and accept that the other 4 will stick out (there's room, they will stick out over the unpopulated pads above the connecotr).

If it's Dell, you need a Dell-specific PSU or an adapter cable.

It looks like this one https://theretroweb.com/motherboard/image/sea … 29324502159.jpg

https://imgur.com/a/2bEBcCO

helios98 wrote on 2025-02-03, 15:21:

[...]

https://imgur.com/a/2bEBcCO

OK, that's regular ATX.

That's regular ATX. If you have trouble finding a new (don't buy a used one, you could be back where you started without knowing it!) power supply with molex power connectors, you can get adapters for SATA to IDE power. Just make sure the adapters are gendered correctly before buying.

It's funny seeing three RAM slots again. I haven't looked at an old motherboard in a long time.

helios98 wrote on 2025-02-03, 14:44:

I have an old Pentium III Slot 1 PC running at 500MHz, built on an Intel SE440BX-2 motherboard. Lately, I have been experiencing some stability issues. When the computer has been off for a while, it sometimes randomly reboots upon startup. However, once it has warmed up, it tends to run fine. Recently, I have also noticed occasional system freezes, graphical glitches, and other odd behaviors.

I suspect that failing capacitors could be the cause, but upon inspection, none appear to be bulging or discolored. Given the age of the system, I believe replacing the power supply would be a good first step to rule out any issues related to power delivery. The current power supply in the system is a Bestec ATX-250-12Z REV.:D7R.

The text in bald, that's all you need to say, friend. 😀

I've fixed a number of these Bestec ATX-250-12Z power supplies. They are actually quite decent units and will happily run even a more demanding a socket A rig with heavy 5V draw. The only problem is, these power supplies are known for developing bad electrolytic capacitors over time. They typically use Teapo SEK (brown with white lettering), CapXon KM (black with white lettering), and Jamicon SK (black with blue lettering, IIRC) on the output side... which is a terrible choice of capacitors for a power supply like this. Apart from that, the rest is built well.

The good news is, this PSU model is relatively easy to recap (replace the capacitors) and can become quite the dependable unit afterwards. So if you're willing & able to do a little bit of soldering, you could end up with a nice PSU. I have 2 of them in service myself, both working quite nicely.
They are also pretty safe to work on, being old non-APFC PSUs (so no single large 400V cap inside that can hold energy for a long time.)

So if you want to go that route, let me know. Can guide you through the process of getting proper replacement caps and where they go.

To anyone else reading this thread, here's that one model Bestec to 100% AVOID: ATX-250-12E - these have a 5VSB rail that goes completely Kamikaze over time and takes out anything connected to it. But the 12Z models are completely different in that regard and therefore don't have this issue... which is why I usually recommend people to fix them.