As requested, a procedure:
I have a V3b (V3 but with split voltage and (previously) a RISE CPU). Below I list the steps I took to convert over my IO. It believe they will also the cover V1 to V3 models
- Unplug unit
- Open up case.
- Remove EMI shroud.
- Remove existing CPU.
- Remove modem.
Do this to give your IO maximum possible available current at CPU. This is a tricky removal and requires two soldering irons at the same time on both ends of the resistor (what I did)
- Remove R302 (near power plug)
- Install .012 Ohm in R302
Mine was already split (V3b), but if you need to split yours (V3 and earlier) I BELIEVE you do this. Please verify elsewhere in this board.
- Desolder R60 and R61
- Solder same to R184 and R185
This cuts the ref voltage (2.5V) to 2.0V for lowest CPU core voltage adjustment point.
- Remove R342 (10K)
- Install 24.9K in R342
- Install 102K in R343
This enables the core voltage.
- Remove R203 (if existing, I had a 1k there.)
- Install 10K in R203
Set the core voltage.
- Remove R202 (10K)
- Install nothing in R202 for 2.0 volts core
- Install 200K in R202 for 2.1 volts core
- Install 100K in R202 for 2.2 volts core
For easy changing of CPU multiplier setting, install switch in SW1
- Remove R130 (0 ohm jumper)
- Solder 4 position switch in SW1 location (near CPU)
Bus Frequency Switch:
For easy changing of the bus frequency, install switch in SW2
- Remove R208 (0 ohm jumper)
- Solder 4 position switch in SW2 location (under edge of modem)
NICE complimenting photos from Tackhead. Show switch settings and item locations.
Check for proper core voltage.
- Plug in unit
- Check voltage on pads of R60 / R61. (near top of CPU)
- One side should read 3.3 volts.
- The other should read your intended core voltage (say 2.0)
- Install CPU
- Boot it
- Hit a CTRL-ALT-ESC to go into CMOS. Check CPU setting and voltage.
- Install modem
- Unplug unit
- Install EMI shroud.
- Close up case.
If I have any errors, PLEASE post them here. I believe everything above is correct to the best of my understanding. Please use you common sense if you suspect a problem.