If you look at the description of pin 81 it says:
"The first function of this pin is the power management
event #, and supports the PCI PME# interface. This signal
allows the peripheral to request the system to wake up
from D3 (cold) state. This pin is backed by VCCH"
So, VCC Help is a voltage that is present even if the computer is off. It should be safe to assume it is the same as 5VSB.

Looks like VCCH powers I/O for a lot of stuff: PCI PME, case open detection, fan PWM control, IR transmit/receive, MIDI transmit/receive. I believe the PME is used by PCI devices to signal the system to wake from sleep (e.g. for wake-on-LAN, etc.) - card pulls the line low.

If the VCCH pin is burnt up, that would likely indicate a short happened through the chip on something powered by VCCH. I'd check for shorts to ground on the pins responsible for the above. Or, maybe something got fried by over-voltage; I could imagine a fan control MOSFET could fail shorted drain-to-gate, and send 12V up the chip's clacker. 😀

Does the board otherwise work? If so, does anything that the IT8705F controls still work?

The board is dead as a dodo - that is, it does power on but no code is being executed. Well, at least no post codes.

There was a black scorch mark on pins nearby. Maybe it was just the byproduct of the leg vaporising but it might also suggest an overvoltage on the 5VSB. I'll check everything that is connected to the ITE, then I guess the next step is to source another one.

Did I understand right and the ITE is also responsible for BIOS communications?

Thanks so far!

tony359 wrote on 2026-07-03, 17:29:

Did I understand right and the ITE is also responsible for BIOS communications?

Only if it's a 440BX-era board or earlier.
And even then, unless it's a VIA chipset, they integrated the SIO into the southbridge even earlier.
On more modern platforms, the BIOS usually communicates through the southbridge.

oh no then, it's a Gigabyte GA-8SR533P

Then I can only hope it's causing some havoc on the board.

tony359 wrote on 2026-07-03, 21:23:

oh no then, it's a Gigabyte GA-8SR533P

Then I can only hope it's causing some havoc on the board.

https://drive.google.com/file/d/1DgDqnQ9vk2kF … Xj3PO8tnf1/view
https://drive.google.com/file/d/1uuv8_V3hYcyV … Kt4tiKEUf0/view
or
https://elektrotanya.com/gigabyte_ga-8sr533p_ … f/download.html

As far as I remember/know from those days:
- The SIO is powered by the +5V STB, so it often burns out if the power supply fails.
- It exchanges some signals before the BIOS is read, so it must be functional for the motherboard to initialize.
- When replacing, the letter indexes must match. Therefore, your "FXS" should only be replaced with "FXS," and preferably also from a Gigabyte motherboard.

the thing has schematics? 🙂 Fantastic! So yes, it is 5VSB.

You think a replacement from online might not work? Does the SIO have some programming inside?

Thanks a lot, I saved the schematics for future reference!

tony359 wrote on 2026-07-04, 09:21:

Does the SIO have some programming inside?

Nope.
At those nanometers, silicone was very cheap for customization.
Asus and Gigabyte liked to order their modifications from Winbond and ITE.
Slightly different pinouts.
For example, to support Dual BIOS at Gigabyte (a watchdog that switches BIOS chips).
Because Intel, VIA, NVIDIA, and AMD would have told them to go to hell, while smaller chip makers were happy to accommodate them.

As far as I remember, FXS is more or less universal. The one starting with "G" is strictly for Gigabyte.

Very cool! I'll keep that in mind! Thanks again!

Well, looks like my theory about over-current on VCCH is probably unlikely. Looking at the board schematic, I see that most of the ITE chip pins that are supplied by VCCH are unused, or used for non-significant purposes. PME is unconnected; case open is only on the IT8705AF (not on F); fan control is unused and instead those pins are used as GPIO for some resistors that give board 'ID' (model?) and one as control of PC speaker (through a couple of transistors). IR TX/RX goes to an optional pin header, which I assume is unconnected. That only leaves MIDI TX/RX, which goes to joystick port, but through 220Ω resistors which would limit any over-current (and therefore be just as likely to burn as the ITE chip).

The BIOS flash ROM appears to be connected exclusively through the SIO - according to the schematic, the address and data lines of the ROM chip only go to the IT8705F - so if the chip is dead, then it's no surprise that the system won't POST.

Man, the location of the IT8705F on that board kinda sucks for rework! Closely surrounded on three sides by plastic connectors! Gonna have to be careful with the hot air if you swap it. 😀

Thanks for looking into the schematics for me! I guess it's good news, it might mean the chip is just dead.

No worries, I seldom use hot-air to remove similar chips. I like more the "chunky copper wire around the legs, flooded with solder + low melt solder". Then I solder the new chip manually, one leg at a time. That saves a lot of stress to the PCB.