Overclocking Celeron 400?



New Member
Can you overclock the Celeron 400? I'm new to the Celeron overclocking deal and I read from a lot of sources that besides the Celeron 300 and 366, recent Celerons are un-overclockable.

Another question I have: Do Celerons run on 66 or 100mhz FSB and will PC100 memory work with these?


New Member
Yep, you can overclock any of them. I have a celeron 400a running at 450 at 2.0v.
Celerons were intended to run at 66 FSB, but you can overclock the chip by increasing the FSB. Depending on your board, you can either do this in the bios (eg. Abit BH6) or directly on the motherboard itself. I have the abit BH6 at 75 MHz FSB; I have tried the mb at 83 Mhz, but my hard drive doesn't like it.
In answer to your other question, yes you can use pc100 sdram with celerons running even at the 66 Mhz FSB (even pc133 would work as they are backwards compatible)
Hope this helps


I am one of the lucky few. My Celeron 400A is running stable at 500 MHz (83 Mhz FSB X 6.0 multiplier). It refuses to boot when I try to run at 600 MHz though.


New Member
So, it looks like the FSB is variable but the multiplier clock is fixed on the chip, is it not? I have been trying to figure out what Intel did to these Celerons.

I plan to overclock my 400a to 450. What voltage should I use, is a standard CPU fan sufficient to cool this modification, and will a Voodoo3 3000 card survive this? I know I have a lot of questions but I appreciate as much help as possible.


New Member
i got a great 400...right now i've got a 8"x2"x1.25" heatsink with 3 fans..i made.

it runs [email protected] or 2.3v depending on how hot it is outside...but now i'm running a peltier at [email protected] and it let me drop the core voltage to 2.00V totally stable...
it runs about 72F under full load.

600 is possibly but u need monster cooling.


New Member
In answer to your questions, here goes.

Yes, youre correct. With any Intel processor made after August 98, the multiplier is locked, and therefore the FSB is the only variable.

What voltage you should use depends on the processor. You should use the lowest possible. So, start at 2.0V, and if it needs more, move it up in the smallest possible increments. Remember, the lower the better, and higher voltage = higher heat.

Given that, the cooling youll need depends on the voltage. In all but the most extreme cases, the generic Intel heatsink and fan are prefectly adequate.

And yes, the V3 3000 should handle it with ease. Default AGP clock is 66MHz (66MHz / 1), so running at 75MHz FSB will give an AGP clock of 75MHz, which should be fine. If youre going to attempt 83MHz FSB, you may run into some problems. On the flip side of that, is that 100MHz is fine, as the AGP clock returns to 66MHz, using a 2/3 ratio (100MHz / 3/2).

Keep the questions coming!
And good luck.

"In the computer industry, there are three kinds of lies;
lies, damn lies, and benchmarks."


New Member
You should not have any problem running your 400 at 450 (75 FSB)and no other changes with stock cooling...

If you want to experiment with higher speeds,
particularly less than 100 and greater than 75, be prepared to have problems like corrupt hard drive..

There are exceptions to this of course, just decide for yourself how much the effort is worth to you..

If you scan this board for people having problems, it usually involves an FSB of ~83...


New Member

I would like to say to the guy with the Voodoo3 3000:

I have a A-Open AX6B Mb with a Celeron 400 @ 500 Mhz. My Voodoo3 3000 runs now @ 175 Mhz with a small cooler attached to the heatsink.

My pc is running Unreal intro for days and it is still stable. My proccessor is running at the 500 Mhz with default cooling methods.

I am pretty happy with this.

fat beat

New Member
i have a celeron 400 running at [email protected] it also runs at [email protected] stable, but my asus v3800 agp ultra doesn't like the high agp bus speed very much. i will test the 600mhz soon with a new ppga adapter with voltage conrols. when i try to hit the 600 with 2.0v it hangs up while the system is booting.


New Member
Our current advice to people is to stick with the 366 for now. There is virtually no chance that you will be able to run a 400 at 100 Mhz FSB. Current 366 PPGA chips have a reasonable shot at 550 though (mine is working fine
. You can probably buy the 366PPGA with slot-1 adapter for less than a 400.

I've also yet to meet a 366 (even slot type) that will not do 458 (83 FSB). True, you have the problem with the non-standard bus speed. On the other hand, if your cards will take it, this overclocks them as well. That can be quite noticable with video. ATI Fury cards seem to work fine at 83 with a ratio of 1/1. 3dfx cards often do as well.

The biggest problem at 83FSB, as has been mentioned, is the hard drives. What really sucks is there is just no reason for this. Tweaking a few settings in the BX registers will make it all work just FINE. I keep thinking I'll write a little program to do that someday.

What you can do, though, is just disable UDMA mode in the BIOS. You really won't be able to tell the difference in speed running your drives at PIO Mode 4, and that works fine. There are other reasons to want the UDMA, but this is long enough!

-=DrFoo {Sysop} Third Wave BBS (941) 355-7136=-


New Member
I paid $70 for my 366 ppga and $15 for an adjustable voltage slot 1 adaptor. It does 550Mhz fine. Where did he get $400 from?


Vlad The Impaler
Beat THIS!!! I got a 12.5MHz 286 running at 1.065MHz! it takes about a week to load 3.11!