These changes will take a V3 (Goo’d bios, WINCHIP, no SW4) to 350 MHz with very minor changes.
Needed: K6-III+ 350 or faster
Lasagna cooler (or eqiv)
1/4 watt 10K ohm resistor.
4’ 24 guage wire
Soldering Iron with fine tip.
Optivisor (unless you have GREAT eyes)
1. Work quickly so you don’t overheat and damage traces.
2. If the area to be soldered has no solder on It, tin and remove excess with solderwick. Keep in mind note 1.
3. Tin all leads before attempting to solder.
4. Use clips or other tools to hold components in place before soldering. The soldering iron will drag them away from where you are working. Fingers are a poor choice for this.
5. Be sure the solder flows on both the board and the component. Keep in mind note 1.
6. All references are given with the CPU socket located in the Upper Right.
1. Remove CPU.
2. Remove R60 and R61 and save. These are located above the CPU socket
3. Move these 0 ohm resistors to R184 and R185 located at the lower right corner of the CPU socket. This provides for split voltage CPU’s.
4. Verify the value of R342. R343 and R343 are located at the top right of the sodimm socket. Should be 10K. R343 should be empty. You will need a resistor equal to the value of R342. This does not need to be a surface mount resistor. You can carefully bend the leads of the resistor and trim the leads so it will fit between the solder pads for R343 and the screw pad for the RF shield. Solder in place.
5. De-solder and remove SW3. Use your solderwick to remove the excess solder and heat all the pins on one side at the same time will gently prying up on that side with a fine blade jewelers screwdriver. You want it to come up on one side, not rip it out by the roots. Repeat on the other side and remove SW3.
6. Remove R130 just below SW1 at the right side of the CPU socket.
7. Solder the dip switch removed from SW3 in place. Set the dip switch so the the middle two switches are ON and the outer two are OFF. This sets the multiplier to 5X.
8. Cut 4 feet of 24 gauge speaker wire. Coil this so that every second turn is in the opposite direction to avoid making It an electromagnet. Solder this in parallel to R302 to boost the available current above 6 amps. The wire is actually a low value resistor.
9. Power up the board and measure the voltage at the lower pin of Q16 and be sure it reads 2V+/-.1V.
10. Drop in your K6-III+, and fan, close it up & test it.
For V4 and V5 owners, all you need to do is set the dip switches on SW4 (located above the SODIMM socket) to both off to set Vcore to 2.0V, then do steps 5 through 10.
The hardware changes will get you to 333Mhz. You can use SOFTFSB to raise the bus speed from 66 to 70 MHz to get 350MHz.
My tests with 23C air temperature gives me 42C CPU temps and 73C board temps near Q16 as read by Motherboard Monitor 5. These temps are safe for continuous duty.