AthlonXP Underclocking for a Low-Power Fix
Chipset Register For Changing The Multiplier
To make all this happen, the motherboard BIOS must activate a few registers to provide the required functionality. If this is not the case, the system simply crashes at the very attempt.
| Chipset | Register | Bit/Function |
|---|---|---|
| NVIDIA nForce2* | F6, Bit 4E7, Bit 4 | Halt DisconnectFID_Change Detect |
| VIA KT133A | 55 | Bit 2=1 |
| VIA KT266, KT266A, KT333 | 95 | Bit 2=1 |
| VIA KT333CF, KT400, KT400A, KT600 | D5 | Bit 2=1 |
| *only works on a few boards |
Unfortunately, it is only possible to change the multiplier on a few motherboards. One of the fastest, the Asus A7N8X-E, crashed every time we tried.
Multiplier In The BIOS: Boot With What?
As the end-user is mostly also prevented from changing the CPU voltage on the fly (without a reboot), a well-functioning combination of multiplier and CPU voltage must already be selected in the BIOS. What makes this difficult is that most motherboards offer the multipliers x5.0 or x6.0 as their smallest value - none of the mobo-makers offers anything below that.
Stay On the Cutting Edge: Get the Tom's Hardware Newsletter
Get Tom's Hardware's best news and in-depth reviews, straight to your inbox.
Current page: Chipset Register For Changing The Multiplier
Prev Page Software For Multiplier Adjustment Next Page System Clock: At Least 100 MHz