Epox 8KHA+ w/ 2600+ @333 : Easy to underclock?

beefkake

Member
Jan 13, 2001
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I have an Epox 8KHA+ motherboard. According to their spec sheet, the motherboard supports up to the Athlon XP 2600+ (Thoroughbred) at 266 MHz FSB. Problem is, I'm realizing it's very difficult to find the 2600+ in the 266MHz version (333MHz versino is MUCH more common).

Question: Can I buy a 333MHz FSB 2600+ processor and easily underclock it to 266MHz FSB, so that it runs within specifications on my motherboard?

Appreciate your feedback. Thanks!!
 

EeyoreX

Platinum Member
Oct 27, 2002
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I may be mistaken when it comes to processors, but RAM runs without a problem at slower clock speeds. My PC2700 is running okay at FSB instead of it's 333FSB on a board that supports only 266. So I think processors should be similar.

Hopefully someone will correct me if I am mistaken here.

\Dan
 

chizow

Diamond Member
Jun 26, 2001
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Originally posted by: beefkake
I have an Epox 8KHA+ motherboard. According to their spec sheet, the motherboard supports up to the Athlon XP 2600+ (Thoroughbred) at 266 MHz FSB. Problem is, I'm realizing it's very difficult to find the 2600+ in the 266MHz version (333MHz versino is MUCH more common).

Question: Can I buy a 333MHz FSB 2600+ processor and easily underclock it to 266MHz FSB, so that it runs within specifications on my motherboard?

Appreciate your feedback. Thanks!!
You wouldn't need to "underclock" it if if the 8KHA+ allowed for multiplier adjustments > 13x. You could just run it at 15.5 x 133MHz to get to 2083MHz. The problem is, the Barton will be unlocked with the "low" multis (6x-13x), while you need the "high" multis to run at 133MHz FSB. If you underclocked it, it wouldn't be a problem, you'd just be getting a lot less out of your CPU at 1663MHz (12.5x133MHz), which would put you at a XP 2000+'s stock speeds in the worse case scenario. You'd be able to up that by increasing your FSB, but the 8KHA+ is still limited by a 1/4 PCI divider which will limit your FSB OC'ing efforts. I remember my unlocked 1700+ T-bred A was limited to the low multipliers even though it was unlocked on my 8KHA+; I'm guessing the same holds true for the newer chips as well (its a mobo limitation).

Personally, I would go with a 266MHz FSB XP 2400+ @ 2GHz which will have a 15x multi. This will give you some nice OC'ing headroom with the high divider, and you'll have the flexibility to push your OC w/out much concern for the PCI dividers. Even at stock speeds, you'll have a faster CPU than a Barton running at 133MHz, and if you upgrade in the future to a board that has full multiplier access (KT400A....X,Y,Z or nForce2), you'll be able to take the CPU with you and adjust its FSB and multiplier as well (based on your memory speeds).

Chiz
 

beefkake

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Jan 13, 2001
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Thanks for the reply- I think I will just stick with the 2400+. Just a note though- I was referring to the 2600+ Thoroughbred, which I would underclock to 266MHz, not the Barton. Does this make any difference? Thanks again!
 

chizow

Diamond Member
Jun 26, 2001
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Originally posted by: beefkake
Thanks for the reply- I think I will just stick with the 2400+. Just a note though- I was referring to the 2600+ Thoroughbred, which I would underclock to 266MHz, not the Barton. Does this make any difference? Thanks again!

Er, I probably just got confused. ;) Barton's on my mind as I think I'm gonna pick one up. Just replace Barton with thoroughbred B though, as there aren't any 2600+ Bartons. :D

Chiz
 

WebDude

Golden Member
Oct 11, 1999
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Originally posted by: beefkake
Thanks for the reply- I think I will just stick with the 2400+. Just a note though- I was referring to the 2600+ Thoroughbred, which I would underclock to 266MHz, not the Barton. Does this make any difference? Thanks again!
I believe the Athlon XP's are multiplier locked (please correct me if I'm wrong on this). So unless you want to do the modification on the cpu (shorting the bridges), you're stuck with the multiplier for that cpu. You can always run a 333mhz cpu at a slower fsb (like 266) with the same multiplier, but you would end up with a much slower system that way. Some chipsets can ignore the cpu's multiplier lock and let you choose whatever you like (like NVIDIA?s nForce2), but so far as I know that doesn't apply to the VIA chipsets.