1st Update: 310ED CPU upgrade success!

[toddyjoe]

As you may recall, I started a thread a couple of weeks ago inquiring about upgrading the processor on a 310ED. The stock processor was a 133 MHz MMX Pentium. Here is my first status update:

First, I want to give a big thank you to Alex Khoury, a/k/a AlphaKilo470. Alex gave me a great deal on an IDT WinChip C6 240 MHz processor to try out. In return for the help of a fellow Thinkpads.com'er, I tried Alex's WinChip first.

I am happy to report that the WinChip 240 works as a fine upgrade for the 310ED. Initially, I needed to change the core voltage DIP switch (S1) from the stock 2.45V to the maximum 3.10V to even get the computer to boot with the WinChip. Once the voltage was changed to 3.10V, it booted fine every time with no problems and never crashed once.

Next, I messed with the CPU speed DIP switch (SW3). With some manipulations of the switch settings, I was able to get all four of the standard 310ED CPU speeds listed in the hardware manual (120, 133, 150 and 166 MHz). With some further manipulations, I was also able to get 125 MHz (50 MHz bus) and 200 MHz (66 MHz bus) without any boot-up or operation problems. I tried one final setting that I thought might get me 233 MHz but I started having problems with it locking up during system start. However, I had been turning the computer on and off all night long and it was getting hot with a completely-drained battery (strictly running on wall-outlet power at this point) so I will try it again another day when the computer has rested and cooled off. I will then post a second follow-up thread. At a minimum, I can say with authority that the 310ED is capable of a processor upgrade to at least 200 MHz without any boot-up problems and without any apparent crashing problems. I feel pretty good for a computer rookie right now!

One point of clarification: In the last thread, it was suggested that the 310 and 315 series use a Socket 7 for the processor. When I opened my computer up, it appears that my 310ED (133 MMX) has a Socket 5, not a Socket 7. I base this on my understanding that the Socket 7 has the one extra pin hole on the inside corner that the Socket 5 does not have... my socket does not have the extra pin hole. In any event, the WinChip still fits.

So what is next? At the same time I got the WinChip from Alex, I found a used and cheap AMD K6-2 380 mobile processor like the one in the Japanese photos from the last thread. Unfortunately, the AMD K6-2 is a Socket 7 processor and has the extra pin my socket cannot accept. But I notice in the Japanese photos that they cut off the extra pin (which I believe is unconnected) when fitting the AMD K6-2 in the 310ED Socket 5 space. Given that I got the used AMD very cheaply, I may cut off the pin and give it a go. I will post a follow-up thread if I give it a try.

Thanks again for everyone's help on this project!

[AlphaKilo470]

Awewsome! Glad to hear the chip runs. Is there any significant increase in performance? The extra megahertz speed as well as the increased primary L1 data cache (WinChip's 64kb as opposed to the Pentium MMX's 32kb) should yeild some results, I would hope.

[toddyjoe]

Yes, at the 166 MHz and 200 MHz settings there is a noticeable increase in performance speed. For lack of a better description, the whole computer just seems to lag a lot less.

I think the machine may be capable of getting the 233 MHz setting as well if I play with the voltages. The hardward manual identifies DIP switch settings for four voltages: 2.35V, 2.45V, 2.90V and 3.10V. However, with four individual DIP switches, there has to be more than four settings. Right now, I am running on 3.10V but I think the WinChip likes to see something more like 3.52V as a base operating voltage. If I still cannot get a complete boot and system operation after the computer has cooled and rested, I am thinking a slight voltage increase closer to 3.5V might do the trick.

[toddyjoe]

Sorry for the double post, but I want to provide some results of the experiments with DIP switch settings for CPU speed on the 310ED.

CPU speed on the 310ED is controlled by four on-off DIP switches on a box on the motherboard identified in the hardware manual as SW3. The manual only shows how to set these four switches for 120, 133, 150 and 166 MHz and does not identify which switches control bus speed or multipliers. Neither the manual nor computer analysis software like Everest can identify the manufacturer of the motherboard.

After playing around with different settings on SW3, the following bus speeds and multipliers are available on the motherboard:

Bus speeds: 33, 50, 60 and 66 MHz

Multipliers: 1.5, 2, 2.5, 3

The first two of the four DIP switches for SW3 (numbered 1 and 2), set the bus speed. The second two of four switches on SW3 (numbered 3 and 4), control the multiplier. The bus speeds are obtained by the following settings on switches 1 and 2:

33 MHz = Switch 1 Off, Switch 2 Off
50 MHz = Switch 1 On, Switch 2 On
60 MHz = Switch 1 Off, Switch 2 On
66 MHz = Switch 1 On, Switch 2 Off

The multipliers are obtained by the following settings on switches 3 and 4:

1.5x = Switch 3 Off, Switch 4 Off
2.0x = Switch 3 Off, Switch 4 On
2.5x = Switch 3 On, Switch 4 On
3.0x = Switch 3 On, Switch 4 Off

It looks like the best processor upgrade you can do with the stock motherboard settings is 3 x 66 MHz, or about 200 MHz. However, I read someplace that WinChip C6s can only interpret whole-number multipliers and consequently treats a 1.5x setting as 4.0x. I might investigate this flaw and see if that can get above 200 MHz.