which is known to run ok on 390E

YES! Success! I guess I've answered my own question. Everything's working now - FSB at 100MHz, basic P-II/300 CPU running at 450MHz, USB, floppy and serial port all functioning OK!

Thank you Sharedoc! It was your comment, that pin 14 served 2 functions, that made me think I should not have lifted it from the board. So I tried again to find the pulldown resistor, and this time I found it! (I'm sure I had probed the same points before but I must have failed to make proper contact - everything's so darned small!) And I also found two open pads, one connected to pin 14 and the other to +3.3 volts! So I removed the 10K-ohm pulldown resistor and soldered a 10K-ohm resistor between these two pads - I tried to use the surface mount one I'd removed, but it was so small I gave up in favour of using a physically larger one.

End result - total success with the P-II/300. Now I'll try again with the P-III/500 and the Celeron 466 to see if anything has changed that makes them work. But even if they don't, 450MHz at 100MHZ FSB is a lot better than 300 at 66 FSB! Here's an image identifying the existing pulldown resistor and pads, should anyone else with a ThinkPad 390E be tempted to try this mod: http://img127.imageshack.us/my.php?image=tp390e100fsbmodrm5.jpg. A 10K-ohm pullup resistor connected between the marked pads gives 100 MHz FSB, and everything works properly and seems stable.

Cheers - Prosit - Kippis

Any input on potential problems of takeing a p3 450mhz 390x to a p3 850mhz cpu? From what I can tell cache, fsb, and form factor are the same

Rather arbitrarily I have chosen to respond here - http://www.wimsbios.com/phpBB2/post42605.html#42605. That thread and this one are both about 390E issues rather than 390X, but the one where I have responded has relatively few posts so far, which I thought made it a better candidate for adding 390X information.

The short answer to your question - 'no problem'!

Hey,
This looks like a great mod, and I'm ready to try it on my 390E... where can I find a 10k ohm resistor though? Can i just move the one that I take off the board up? Or is that not a 10k ohm. Can I just use one from Radioshack like this one?
http://www.radioshack.com/product/index ... age=search

I_am_banana,

If you can transfer the existing surface mount pull-down 10K-ohm resistor, (shown in the image linked to above as 'remove this resistor'), to the pads indicated for the pull-up resistor, that's the neatest solution. But the resistor is very tiny, and resoldering it is a bit of a challenge! If you can't get that to work, (or you lose it, which is easy to do!), then just get the smallest (lowest wattage) 10K-ohm resistor you can find and use that. The Radio Shack link you show is for a 1/4 watt resistor - that would be fine if you can't get the smaller 1/8 watt one.

If you haven't already done so I'd suggest you read my posts on pages 53 and 54 of this tread - http://www.wimsbios.com/phpBB2/topic4046-780.html - since I found the 100MHz FSB mod to my 390E to be only partially successful! Actually it wasn't the FSB mod that was the problem, but rather the fact that I haven't been able to get a P-III CPU to run properly - the problems I encountered are in that thread. I was able to get the original P-II/300MHz CPU to run at 450MHZ after the mod, but none of the higher-speed P-IIs (333, 366 or 400) would run overclocked by 50%. So, unless you can get a P-III to run properly, you could achieve the same (or marginally better) upgrade effect by staying with the 66MHz FSB and using a Celeron 466 CPU! I don't know what it is about the 390E and the P-III CPU, but they just don't seem to work together as you'd think they should - after getting the FSB to 100 of course. If you decide to try the mod I'll be really interested to hear if you are able to get a P-III running satisfactorily.

For now I've pretty much given up on trying to get my 390E past the 450MHz that I have now with the original P-II/300. Instead I went to eBay and picked up a 390X for a good price, and now I have it running just fine at 850MHz with a 850/700 speedstep CPU modified per sharedoc's instructions! In the BIOS and in DOS the CPU shows as 700MHz, but strangely once booted into Windows 98SE it's running at the higher 850 speed without any need to run the DeepSleep utility! And that doesn't seem to be a fluke since it's been at 850 every time after booting to Windows. In DOS I can get it to the higher speed by running DeepSleep.

If you do try the modification, and especially if you then try a P-III CPU, please post your findings!

booting every time 850 - Win98SE.... I wonder why.... this is interesting

Sharedoc,

Yes, with Win 98SE it boots at 850 every time, goodness only knows why, but I'm happy! In DOS, "dsleep.exe" will force it from the initial 700 state to 850. But, unfortunately, Windows 2000 seems to be a problem!

I just set the same system up with Win 2K recently and it stays at 700MHz after booting. Running the Win XP/2K version of DeepSleep seems to work, in that there is a pop-up displayed by the program that says the CPU is running at close to 850 - it shows different values in the 840's - BUT the system then freezes at that point and has to be shutdown with the power switch!

This seems very similar to what 'RedScorpion' reported with a 390E on which he had made the 100MHz FSB mod, and which was running a modified 600/500 speedstep CPU with Win XP - see the 5th. post on the page http://www.wimsbios.com/phpBB2/topic4046-810.html. Can anyone offer any suggestions as to what might be the problem? Has anyone had experience with using DeepSleep under Win2K or Win XP?

I could add Vista to the lista (hehe, I added a to make it rhyme).

Hi can you post me a picture where exactly is cy2285 or guide me how to find it. I surch for it but cant find it. Discover chip cy2309 around the CPU socket.

I realize this is a really, really ancient thread but hopefully it'll get bumped to the top and someone can help me out.

I have an IBM Thinkpad 390e (2625) that I have been rebuilding. I sourced a new casework for the bottom, and by chance I found an additional memory module (it now has 196mb RAM), put a spare 30gb HD in, and salvaged a DVD/CD-RW from a dead sony Vaio to replace the standard CD-ROM drive (the ports were the same and lined up exactly, although cosmetically it's far from the same - it still looks good though and I can post pictures if anyone cares to see). Finally, I've decided to ditch the mini-PCI modem card and install a mini-PCI wireless network card (also salvaged from the dead Vaio). The card fits and Windows 2000 detects it just fine. I'll need an appropriate driver but "so far so good". Finally, some kind soul on eBay sold me a NOS battery for $10 that holds a four hour (!!!) charge. Yes, that's right - four hours! I've tested it!

I'd like to install a new processor and more RAM to facilitate an install of XP: I know from experience that XP is really grueling to try and use on anything sub-400mhz (even with eye candy turned off).

So here are my questions: I can source 650mhz CPUs fairly regularly; they're the right form factor, but of course the question is...how do I go about installing? I'm guessing I can't simply install the CPU and expect it to work, so what roadblocks are in my way? Will I have to adjust jumpers? I know they're not the desktop PC kind, that if I do I'll have to cut on the motherboard and possibly bridge others. What about the BIOS? I think the laptop is flashed to the latest revision. Once done can I add more than 256mb RAM? Should I post up images of the laptop?

Thanks all, I hope someone sees this old thread and can help out!