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Has anyone here got a 2.5a P4 working on a Th7-II?

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Apr 4, 2002
It has been suggested elsewhere that the 2.5a should work on a TH7-II even though the board only supports a 24x multiplier.

However, is anyone out there currently running this combination? and if so what kind of results have you had? as i am very tempted to buy one of these CPUs

Many thanks for any help offered

I was interested in the same thing and asked Abit. This is what I got last night:

Dear sir,
Thanks for your mail.

1.Please go to our website to download the new BIOS th7hbf.bin http://fae.abit.com.tw/eng/download/bios/th7-ii.htm

2.The TH7II can use new Celeron 2.2 in the Board.

3.Th7II can use Pentium 4 2.5GHz (400MHz FSB) in the Board .

Best regards,

Some friends of mine use such a CPU on the TH7-II as well but if they pass the 3GHz limit the CPU does not run Prime stable at any kind of voltage...

Hope this helps.

whats a 2.5a I only know of a 2.53. 133 fsb. the th7II will run any chip up to and possibly including the 3.06 chip. really good board as it turns out.


yea as long as the pins are the same ans your mobo can supply the right voltage, i belive all you have to do it add the cpuid to the list in the bios ive been looking at them this morning for the th7II in there old bios
On the Th7II all the p4 chips will work with no mods to anything..
Is that clear.............:eh?:

Let me clarify with a 2.4 gig chip the mult is 18 x 133 fsb which = 2400 with a 2.53 chip the mult is 19 x 133 or 2.53 so with the current limit of 24 the board should do 3.2 gig...

Hope that helps you understand this board


The question Spud-work is asking is the same one I asked a while ago and got the same confusing replies.

The 2.5 uses a 25 multiplier the TH7-II stops at 24 WILL IT WORK? IS THE QUESTION, not quess's, but facts, is there anyone out there who has done it and got it to work?

In theory it should because the chips are clock locked, but can you be sure, who wants to spend $250 to find out it does not.
if the 2.53 was a 100 mhz fsb then yes the mult would be 25. its not its a 133 mhz chip so 19 repeat nineteen 19 thats what the setting would be on the board in the bios.

mult 19
fsb 133
agp pci set to fixed
mem set to 300 which will run your ram at 800 same as original. set it to auto if you want to o/c your ram

its a no brainer

Why do you talk about a 2.53 which I use, when the question on the table is about the 2.5, not the same chip, lets stick to whats relevent to the subject and not about that which is NOT!

Now that is a no Brainer!
I havn't heard of a 2.5 chip 100 mhz fsb is this something new like a celeron that is about to be released or just got released.
I asked in a previous post what it was no one responded. I usually try to keep current.

The 2.5a and 2.6a have been out for a while now.
They are not Celeron chip they are P4 northwood with 512k l2 cache.

P4 2.5a = 25 x 100fsb
P4 2.6a = 26 x 100fsb

My mistake.. didn't know there were those two units.
For the th7II I wouldn't go near them , not when you have the 133 bus chips and its not really overclocking.

you learn something every day..

No worries Logger, too many chips out there to keep track of, I have heard these chips are killer overclocker too (2.5, 2.6)
dam shame we can't use them.

But you know something! there is a small chance they could, because clock-locking would keep them at 25 and 26 multiplier and then you would just have to set the bus speed, don't know, can't aford to buy one and find out.

Go to the CPU data base and see what the 2.5's are doing there is one that is at 3500, not too shaby.

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I would not use 133MHz FSB CPUs on the TH7-II. You have to turn your memory to 300MHz in the BIOS.

Little example:

25x120MHz=3GHz --> 480MHz RAM speed (it is possible to keep the RAM @ 400MHz!!!)

19x157MHz=3GHz --> 471MHz RAM speed (RAM set @ 300MHz)

I heard

So there is much more playroom in the top speed section...

Also ALL 2.5 CPUs are C1 steppings!!! That is not the case when you look at a 2.53 CPU...

I hear what's your saying, I wanted to get a 2.5 but had no clue if it would work and still don't:(.

You sure about that C1 stepping? my 2.53 is not the same chip as the 1.8A I had before, bachside resisters are different.

Tell you what though! this chip smokes at 2.85, no complaints here, but I sure would have liked to know how far a 2.5 would oc.
3GHz with default vcore should be no problem when you use a 2.5 C1 which is definetly only available in C1 stepping!

I will get such a chip as well. It will work! I have 3 friends running a 2.5 (100) on a TH7-II...

Oh well, there are a lot of 2.53 CPUs out there which perform very well! A friend of mine had one running on an Asus P4PE @ 3.4GHz with 1.75v actual...

But it is not guaranteed that a 2.5 will hit 3GHz with 1.5v but you have a very good chance...

BTW: I heard of RDRAM running cool @ 125MHz with 400MHz setting in the BIOS. In theory this would be 166MHz when set to 300MHz in BIOS but the RAM didn't make that stable. It did only about 155MHz stable which is an unaccaptable loss...