Lowering Vcore on MOBOs without bios Vcore control

Cooling Processors quietly

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osl
Posts: 28
Joined: Sun May 16, 2004 11:08 am

Lowering Vcore on MOBOs without bios Vcore control

Post by osl » Mon Jul 12, 2004 12:03 pm

Is it possible to lower 1,58V default Vcore to 1,35V (true XP-M 2400+ 35W Vcore) using some simple mod (for the KA7500C SMPS controller) on KM400 Flex-ATX motherboards, like PCCHIPS M851LU, Matsonic MS8188E, Shuttle MK40VN ?

Reason ? I think the following picture explains it all !

http://www.sitecenter.dk/dahl_larsen/ns ... 1small.jpg

OSL
"Small is beautifull - silence is art"

osl
Posts: 28
Joined: Sun May 16, 2004 11:08 am

Post by osl » Sat Jul 17, 2004 4:47 am

:D

The KA7500C undervolting mod works perfectly. One (5 cents) 270K resistor betwen pin 1 and pin 12 and Vcore is down 0.3 V (from 1.58 V to 1.28 V) and temps down 7 degrees (and everything is stable). Tests show that there is a nice linear correspondance between Vcore and the resistor value: Vcore = 1 + (R/1Mohm) V

Underclocking (or undervolting) made easy.

OSL

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