Since you didn't describe your troubleshooting steps so far: Have you tried turning it off and back on again resetting CMOS after switching the processor?

How many GPUs have you tried?

Well, I was hoping for some help with troubleshooting this problem. I did clear the cmos to see if it would somehow find the cpu but no luck. But what else is there to try? I mean take the 1.9 processor for instance, it works fine in it's original board but the two other boards refuse to boot with it installed. Kolderman, thanks for the idea of changing video cards, it honestly didn't occur to me. Thats the kind of ideas I was looking for.

So, I've reset the cmos on both boards that have the lower clocked processors. I have tried several different AGP video cards plus a couple of PCI cards. I have switched around several different RDRAM combinations and tried a couple of different power supplies. The 1.9 cpu refuses to boot in any board except it's original Intel motherboard. I still need to explore the bios version differences but even if the board didn't recognize the cpu shouldn't it still boot? Anybody have any idea of what else I can try? I did get the 1.7 chip to work in the 1.9's original board so the problem seems to be with the 1.9 cpu, the other boards just don't like it for some reason.

Look here : https://www.cpu-upgrade.com/CPUs/Intel/Pentiu … 31PC037G0K.html

I don't know why but they state that the upgrade chance to the 1.9ghz version is 35%. That's pretty low and I guess it means that a lot of boards need a bios update to get it to work (newer stepping etc?)

Maybe it would help if we knew exactly the three relevant parameters:

- which boards and revisions
- which BIOS versions are running on them
- which P4 steppings do you have (S-Spec is fine if you don't know the exact stepping)

There were 4 steppings of Willamette, and it's entirely possible that a lower-clocked CPU is in fact newer than a higher-clocked one. However all things being the same the 1.9 is most likely to be the newest, and if that means a stepping unknown to the other BIOS, the mystery might be solved. The fact you're using OEM boards doesn't help - Intel in particular tended to make its boards not boot if an unknown CPU was detected.

Hey, thanks for all the help and suggestions. from everyone. Meljor thanks for the link . I have found some other old posts mainly from Dell support sight that upgrading to the willamette 1.9 was problematic. Strangely enough Dell was recommending either the 1.8 or 2.0 as being compatible upgrades but not 1.9 . I am going to explore bios updates for these boards when time permits but will probably just use them as is for the time being. Can't believe there is much difference between the 3 cpu's anyway. Just found this kind of strange.

Well some of the comments on here led me to try a bios update---looking at you dionb thank you--and after moving to P14 bios the 1.9 is working well on all boards. It's good to have other people give input when you are stumped. problem solved