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Old 09-18-2008, 05:35 AM   #41
PCBONEZ
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Default Re: GA-8S655FX with very hot FET

Could you tell if USB ports, Video, Sound, LAN were working?
That's the point of it.
It's a EASY QUICK way to tell if you have a hardware or windows problem.
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It's open source.
If you want an advance testing package you can make one.
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Old 09-19-2008, 01:48 AM   #42
anonbeat
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Default Re: GA-8S655FX with very hot FET

I found yesterday that a friend have the same board. He is having problems but finally found it was couse a bad memory module.
I told him to check the fet that gets so hot and also measure the voltage in the pins.
He told me the FET doesnt get hot and the voltages are the same as the ones I got.
D - 3.32v
S - 1.90v
G - 6.30v

For my understand this indicates that the FET is working fine and there is someting in the FET output that is consuming too much. It could be the southbridge. I need to discard its not something out the southbridge.
any ideas ?
can be the FET ?
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Old 09-19-2008, 07:01 AM   #43
Wizard
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Default Re: GA-8S655FX with very hot FET

hot FET can also mean bad regulator controller IC pumping bad signal to FET. I had dell D600 fry a totem-pole FET IC (blow a crater) every time I swap it, fix was replace both regulator controller IC and this FET IC. Now I have a working D600.

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Old 09-20-2008, 01:19 AM   #44
davmax
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Default Re: GA-8S655FX with very hot FET

If the MOSFET is regulating the controller should be OK. Two prospects

1. Southbridge load too heavy or anything else loading up the circuit.
2. Possible oscillation in MOSFET regulator circuit. Least likely.
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Old 09-20-2008, 07:33 AM   #45
PCBONEZ
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Default Re: GA-8S655FX with very hot FET

This is what I think too.

Quote:
Originally Posted by davmax
1. Southbridge load too heavy or anything else loading up the circuit.

You need to find a diagram/schematic of chipset and explore inputs/outputs.
I don't know where you'd find one for SIS.

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Old 09-20-2008, 09:53 AM   #46
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Default Re: GA-8S655FX with very hot FET

I found the datasheet for the SiS 960 but nothing on the SiS 964 or the complete chipset SiS 655 Fx
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