I have a friend who owns a Dell Dimension 4300. It originally came with a Pentium 4 1.7GHz processor and after running across a few faster processors, I decided to try upgrading the CPU on the Dimension 4300. I did a bit of research and found a forum that mentioned the maximum CPU speed was a theoretical 2.0GHz for the system. So, I stuck in a 2GHz and it worked flawlessly. I also had a 2.4GHz Celeron that we yanked out of one of his newer computers and stuck that in just to see what it would do. It worked flawlessly as well.
I got to looking at the processor specs between the two and noticed that the FSB on the two processors was 400MHz. I also had a 2.60GHz with a 533MHz FSB and it did NOT work in the system. (I realize there is more to the correlation between the FSB and motherboard but I didn't feel like researching it too extensively. It's more fun to "plug it in and see what happens".)
So, I have decided that the Maximum processor speed for a Dell Dimension 4300 is going to be the highest processor with a 400MHz Front Side Bus. Like I said earlier, I used a 2.4GHz Intel Pentium 4 Celeron. BUT, I don't see why a full blown 2.4GHz Pentium 4 with a 400MHz FSB wouldn't work in the same system. I highly doubt there are any 2.6GHz processors with a 400MHz FSB, but in theory, if there is one, it will most likely work fine in the Dimension 4300.
After reading through a comment below, someone mentioned that they were able to get a 2.8GHz 400MHz FSB Celeron to work without a problem. So, a 2.8GHz P4 should run just fine on a Dimension 4300. I also ran across the Intel Pentium 4 Processor Finder which allows you to filter the list of P4's based on various criteria such as the FSB. I was hoping to find a 2.8GHz P4 with a 1MB cache but the highest 400 FSB P4 built was a 2.8GHz with the following specs:
|sSpec#||CPU Speed||Processor #||Cores||Bus Speed||Mfg Tech||Stepping||Cache Size||Package||PCG|
|SL7EY||2.80 GHz||N/A||1||400 MHz||0.13 micron||D1||512 KB||478 pin||N/A|
Several folks have posted in the comments that a full P4, SL7EY WILL work in the 4300 as well as the Dimension 4300S! In order to accomplish this though, you MUST first update the BIOS to version A06 which will work for both the Dimension 4300 and 4300S.
I had a brain fart idea and decided to post the Dimension 4300 Specs... Why I didn't do this before, I don't know. The processor info is kinda useless at this point given the tested info in the comments, but some of the other stuff might be note-worthy.
Dimension 4300 / 4300S Recap:
Maximum Known Working Upgradeable CPU: 2.8GHz Pentium 4 with 400MHz FSB known as SL7EY OR Any socket 478 processor with a 400MHz FSB.
I hope that answers any questions regarding the maximum cpu speed that a Dell Dimension 4300 can be upgraded to! (Also, Thanks to everyone who has helped by posting their findings in the comments!)