Changing The Core Voltage On Any Slot1-Motherboard
Now what do all the people do who don't have, want, like the Abit BH6? Well, if you want my honest opinion, I'd recommend them to run their CPU at 450 MHz and be happy. If this should not comply to you, there's still no reason to trash your current board and go buy the BH6. You can change the voltage to at least 2.2 V with a little trick. The voltage detection of the motherboard works via 5 CPU pins, which are either connected to Vss or to nothing. Now covering a CPU pin with tape, as discussed in my B21 article , simulates a 'not connected' or 'open'. Unfortunately you cannot simulate a 'connected to Vss' or 'closed' condition, which impairs you a little bit and makes the solution in the BH6 still more flexible.
First the theory. The 5 pins used for the voltage detection are pins VID0 - VID4, 'VID' standing for 'Voltage Identification'. The following table shows where to find the pins on the Slot1-connector:
|Pin Description||Pin #|
The next table shows you how the pins have to be set up for voltages between 2 and 2.3 V.
|connected||connected||connected||connected||not connected||2.00 V|
|not connected||not connected||not connected||not connected||not connected||No CPU plugged in, BIOS error message|
|not connected||not connected||not connected||not connected||connected||2.10 V|
|not connected||not connected||not connected||connected||not connected||2.20 V|
|not connected||not connected||not connected||connected||connected||2.30 V|
As you can see, the default 2 V setting that is supplied by the CPU has already got VID0 'not connected', which cannot be changed by taping the pin. This is why you cannot reach 2.1 V or 2.3 V, both need VID0 'connected'. However, you can achieve 2.2 V, by covering the pins for VID2 - VID4 = A119, B119, A121.
I do not recommend increasing the voltage over 2.2 V, the next possible step for a non-Abit-board-owner would be 2.4 V, which is definitely way over the limit. Please also keep in mind that this operation here is certainly only for people who know what they are doing. I do not take any responsibility for damaged CPUs or motherboards. As a matter of fact, sticking to the default voltage and running a PII 300 at 450 MHz is already cool enough.