Model: BIOS, p5hxa12q, Version 1.2q
Operating System: (Note: might work with other versions of this os.)
File: p5hxa12q.exe
Comments:
How did P5HX-A PCB 1.X support P55C: P5HX-A PCB 1.X ( included the earlier PCB versions) reserved the function of P55C on board in its original design, you can through modifying some resistors and components to
provide 2.8V voltage
1. Add U37 (Sharp PQ7RV4) near U6
2. Add R62 Resister value 2Kohm
3. Add R61 resister value 1.6Kohm for P55C 2.8V core voltage
(only provide 2.8V on P5HX-B PCB 1.X)
4. Change JP2, JP3, JP4, JP5 from short 1-2 to short 2-3 to separate CPU core, I/O voltage
5. About 166MHz, 200MHz jumper setting, please refer to manual
6. Maximum frequency supported by P5HX-A mainboard is 200MHz(66MHz x 3). Please refer to manual for jumper setting of P55C. Note: P55C core voltage 2.8V