Strange Desktop Motherboard problem

Hello everyone hope you are doing well,

i have a ddr2 I31GM4-LF REV3.0
it seems everything working fine except that USB,SATA,PCI Devices can not be read or detected by the computer but the strange thing that there's voltage present like the usb 5v and the pci 3.3v i believe its something related to the southbrgide chip.
as i know if the southbridge is faulty the pc will not turn on in the first place.

by the way i did replace couple cup's and rams and they works fine. and i did check mosfets and caps and they are good.
i don't know what to check else i'm stuck

so i hope if anyone else saw a problem like this before or have tips or solutions for me.

i know the motherboard don't worth fixing it it's only for the purpose of learning.

best regrades ^^

You try another sata cable ? BIOS settings dont have drives/ports disabled ?

Regards, Dana.

It seems to be some component failure.
I have a similar problem with my AsRock MB.
The computer will not detect anything plugged into my PCI slots . USB / SATA .... are all fine.
The PC works fine.

danadak said:

You try another sata cable ? BIOS settings dont have drives/ports disabled ?

Regards, Dana.

Click to expand...

of course i did try other sata cables and other hard drives.
and it's not possible to enter the bios since can't use any keyboard.

thank you for your reply

Ramussons said:

It seems to be some component failure.
I have a similar problem with my AsRock MB.
The computer will not detect anything plugged into my PCI slots . USB / SATA .... are all fine.
The PC works fine.

Click to expand...

i'm glad im not the only one facing this problem .

i believe its a component failure too but where's is that sneaky one.
i'm thinking to remove the southbrige chip if nothing helps.

thank you for your reply mate ^^

I assume you have done a full CMOS reset/clear?
It is possible that only some logic part has died in the southbridge but not the entire chip.

sagor1 said:

I assume you have done a full CMOS reset/clear?
It is possible that only some logic part has died in the southbridge but not the entire chip.

Click to expand...

yes i did many times.
can you tell me what do you mean by a logic part in the southbridge ? for example like a mosfet or an AC connected to the chip ? or a part inside the chip itself ?

I'm thinking inside the chip. Some bad hardware fault may have produced some voltage on some pins that "broke" some interface lines of the chip.
It could also be a failure from heat or just plain "aging" of the chip.
It is impossible for most people to test that chip, unfortunately.