The penultimate idea
Is there 2.5V on this capacitor when Motherboard is on?
This voltage is mainly used for the clock generator.

And the last idea.
This is the power supply of the AGP.
3.3V - AGP2x 3.3V (or no card)
1.5V - AGP4x/8X 1.5V

If there is, then I would most likely suspect a proprietary monitoring chip from Asus.
Sorry

shevalier wrote on 2025-05-03, 14:03:

And the last idea. This is the power supply of the AGP. 3.3V - AGP2x 3.3V (or no card) 1.5V - AGP4x/8X 1.5V […]
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And the last idea.
This is the power supply of the AGP.
3.3V - AGP2x 3.3V (or no card)
1.5V - AGP4x/8X 1.5V

If there is, then I would most likely suspect a proprietary monitoring chip from Asus.
Sorry

0.27v capacitor
1.5v AGP with card installed

Kittyboy wrote on 2025-05-03, 14:46:

0.27v capacitor

2SC4672
NPN EPITAXIAL PLANAR TRANSISTOR in SOT-89

But I repeat, there should be no voltage in standby mode.
The clockgen is powered only during operation state.

shevalier wrote on 2025-05-03, 16:06:

2SC4672 NPN EPITAXIAL PLANAR TRANSISTOR in SOT-89 […]
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Kittyboy wrote on 2025-05-03, 14:46:

0.27v capacitor

2SC4672
NPN EPITAXIAL PLANAR TRANSISTOR in SOT-89

But I repeat, there should be no voltage in standby mode.
The clockgen is powered only during operation state.

The transistor between socket 1&2 measures 3.3v with power on, 0.0v standby. Socket #2 Pin #15 is 0.05v standby and 1.6v power on. The cap with power on is 0.5v.
The point you marked to the cap is 2.5v power on. The others are 3.3v. (see image)

You have tried 66fsb yes?

myne wrote on 2025-05-04, 02:48:

You have tried 66fsb yes?

Good idea.

Kittyboy wrote on 2025-05-03, 23:41:

Socket #2 Pin #15 is 0.05v standby and 1.6v power on. The cap with power on is 0.5v.
The point you marked to the cap is 2.5v power on.

The ISL I pointed out is not the clock generator in the photo, but the PWM controller next to the ATX connector.
But if there are 2.5V on the capacitor, then it's not a problem - the voltage is normal.
It would be worth starting measurements with the processor core voltage.
There should be 1.5V there.
But if it heats up, then most likely it is.

I think it's the AS99127F monitoring chip.
But there are many modifications, and finding a compatible one is a very unpleasant task.
Because you can only find out by replacing it.

shevalier wrote on 2025-05-04, 03:43:

Good idea. […]
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myne wrote on 2025-05-04, 02:48:

You have tried 66fsb yes?

Good idea.

Kittyboy wrote on 2025-05-03, 23:41:

Socket #2 Pin #15 is 0.05v standby and 1.6v power on. The cap with power on is 0.5v.
The point you marked to the cap is 2.5v power on.

The ISL I pointed out is not the clock generator in the photo, but the PWM controller next to the ATX connector.
But if there are 2.5V on the capacitor, then it's not a problem - the voltage is normal.
It would be worth starting measurements with the processor core voltage.
There should be 1.5V there.
But if it heats up, then most likely it is.

I think it's the AS99127F monitoring chip.
But there are many modifications, and finding a compatible one is a very unpleasant task.
Because you can only find out by replacing it.

The capacitor with power on, not standby was only 0.5v

shevalier wrote on 2025-05-04, 03:43:

Good idea. […]
Show full quote

myne wrote on 2025-05-04, 02:48:

You have tried 66fsb yes?

Good idea.

Kittyboy wrote on 2025-05-03, 23:41:

Socket #2 Pin #15 is 0.05v standby and 1.6v power on. The cap with power on is 0.5v.
The point you marked to the cap is 2.5v power on.

The ISL I pointed out is not the clock generator in the photo, but the PWM controller next to the ATX connector.
But if there are 2.5V on the capacitor, then it's not a problem - the voltage is normal.
It would be worth starting measurements with the processor core voltage.
There should be 1.5V there.
But if it heats up, then most likely it is.

I think it's the AS99127F monitoring chip.
But there are many modifications, and finding a compatible one is a very unpleasant task.
Because you can only find out by replacing it.

Just to be clear, I attached a photo of the capacitor I am referring to. I just now measured it with .25v and dropping with power on, I cycled power twice, same result.

Sounds like we have a winner.

How many ohms?
I'd be guessing either that cap, or an SMD nearby is short.
Time to look at the boardview and poke around

If you have Kicad, the files I converted show component values.
I don't think boardview does.

myne wrote on 2025-05-04, 04:04:

Sounds like we have a winner. […]
Show full quote

Sounds like we have a winner.

How many ohms?
I'd be guessing either that cap, or an SMD nearby is short.
Time to look at the boardview and poke around

Capacitor with power on (not in standby), and power off, both reading 2.xxx K Ohms. What value capacitor is this? (see image)

Its looking like this
Can you test bipolar transistors without desoldering its?

shevalier wrote on 2025-05-04, 04:27:

Its looking like this
Can you test bipolar transistors without desoldering its?

I'll go take another photo of the area you marked up for clarity, I'm not able to accurately view this. Also, if I test these locations, should I assume it is without the CPU installed and power on?

see image

Kittyboy wrote on 2025-05-04, 04:38:

shevalier wrote on 2025-05-04, 04:27:

Its looking like this
Can you test bipolar transistors without desoldering its?

I'll go take another photo of the area you marked up for clarity, I'm not able to accurately view this. Also, if I test these locations, should I assume it is without the CPU installed and power on?

First, measure this red and green on a fully turned on motherboard.

I still think it's more likely a low resistance cap.
It's a 25yo electrolytic.

There's a fair chance pulling that cap off will result in 2.5v.
Probably not stable, but correct.

I'll look for the value when I'm home.

Kittyboy wrote on 2025-05-04, 04:50:

see image

Batter image attached

myne wrote on 2025-05-04, 04:55:

I still think it's more likely a low resistance cap. It's a 25yo electrolytic. […]
Show full quote

I still think it's more likely a low resistance cap.
It's a 25yo electrolytic.

There's a fair chance pulling that cap off will result in 2.5v.
Probably not stable, but correct.

I'll look for the value when I'm home.

The ADC of a multimeter usually has dual integration and does not react particularly to pulsations.
Even if there is a square wave from ground to power, it will show much more than half a volt.
The clock generator at 2.5 V consumes only up to 0.2 A

That goes to several places on the board.