Thorry
04-14-2003, 02:45 AM
I need some help with a K7S8X vDDR mod.
High-res image of mobo:
http://www.asrock.com/product/amd/images/K7S8X-FACE.jpg
Bottom-right corner is a MOSFET where I measure vDDR.
Go left from there to where the slots end I see U32 which is a National LM431.
Datasheet:
http://cache.national.com/ds/LM/LM431.pdf
When I connect vRef to GND via a resistor the vDDR voltage!drops! On vRef and output I do not measure 2.77 vDDR but 2.55. But as the output voltage drops the vDDR voltage drops.
Also I read http://www.overclockers.com/tips954/ where the LM431 is also used. But this doesn't help much.
When I connect vRef to +5 via a resistor the voltage doesn't change at all.
Also there is an IC near the MOSFET where I measure vDDR but there is no brand on it at all. It says 4500M 252513 on mine but on the photo it says 4500M 242303. I couldn't find this IC but I'm guessing it's an PowerFET.
I could try lifting the vRef pin from the mobo to increase resistance between vRef and GND. But I would like to be certain before trying.
Can somebody help me with this mod?
High-res image of mobo:
http://www.asrock.com/product/amd/images/K7S8X-FACE.jpg
Bottom-right corner is a MOSFET where I measure vDDR.
Go left from there to where the slots end I see U32 which is a National LM431.
Datasheet:
http://cache.national.com/ds/LM/LM431.pdf
When I connect vRef to GND via a resistor the vDDR voltage!drops! On vRef and output I do not measure 2.77 vDDR but 2.55. But as the output voltage drops the vDDR voltage drops.
Also I read http://www.overclockers.com/tips954/ where the LM431 is also used. But this doesn't help much.
When I connect vRef to +5 via a resistor the voltage doesn't change at all.
Also there is an IC near the MOSFET where I measure vDDR but there is no brand on it at all. It says 4500M 252513 on mine but on the photo it says 4500M 242303. I couldn't find this IC but I'm guessing it's an PowerFET.
I could try lifting the vRef pin from the mobo to increase resistance between vRef and GND. But I would like to be certain before trying.
Can somebody help me with this mod?