I ran a Barton core on a KT266A mobo for a while. It didn't recognize the CPU, but it worked fine. I had to do a socket wire mod to get a high multiplier for the CPU to be clocked decently though. Important to have a CPU with unlocked multi or make sure you get one that is designed for 133 MHz FSB.

Going way back to KT133A or so is going to be more questionable though. Worth a try of course.

I'm using an XP-M 2500+ (rated at 1.8ghz) in my KT133a Based board right now. This one is based off the Barton core, and I have also used T-breds aswell. The problem is that at this stage, the sockets are only wired up with a 4 bit FDIV, meaning you have a max selectable multiplier of 12.5. This yields a net clock of 1.67ghz. I incorrectly assumed that if a get a chip with a higher default multiplier it would run at that setting. I was never able to figure out if this was the result of using an unlocked chip, or if it would be the same with a locked one. I used to have a lot of stability problems since I was using a grossly underrated power supply, and as a result in the beginning I only ran at 11.5x100. Once those issues were addressed and the machine tuned up another 500mhz plus the faster FSB settings, I have kinda put the whole wiremod thing on the back burner. I find that my 1.67ghz AXP is comparable to my 2.6ghz P4.

Hmmm... are Bartons supported by your BIOS? Even after the update mine officially supports only up to Palomino 1800, but like I said, in theory most others should work as well. I figure MSI probably just never bothered to test them.

Yeah they work, just not offically. I have an updated bios and it didn't detect it either, it just says Unknown CPU. AMD did a pretty good job of keeping the Socket A processors cross compatible. In my experience as long as the voltage is set properly it should work. Every chip I have tried runs at either 100 or 133 FSB, even if they are rated for higher. The only issues left is one of multipliers.

At this point you have managed to pique my curiosity, I have always wondered how the BIOS and such would deal with a wiremod. Maybe I'll just bit the bullet, grab some wire and a tweezers and give it a go.

Havent seen this topic on time, but let me tell you that bartons will work flawlessly on old kt133a motherboards. The only trick is to get an unlocked mobility barton 2600+ and up; that way the default multiplier is >13x which enables multipliers up to 24x. Here is the multiplier cross-reference:
http://mysite.verizon.net/res0exft/Multiplier … s_reference.htm

And here some more info:
http://mysite.verizon.net/res0exft/cpu.html

That's kind of frustrating.. I saw that my BIOS gave me a max multiplier of 14x so I picked a XP-M 2500+ figuring at the worst case I could default it.. well turns out the 14x setting is actually mapped to a lower setting (to make the 1400mhz 100fsb Athlon work), and again making it peak at 12.5x. I wish I would have known better. Last time I was messing with pin-mods the wire I had was too thick of a gauge for me to stick the processor back in after setting in 4 or 5 different pin-jumps. I think I had pretty much isolated the pin that enables the 5th bit, maybe next time I take it apart I'll just make the one jump and see if I can get up to the 2ghz range.

At one time, I had a pair of Gigabyte GA7-ZXE systems on hand at the same time, one Rev 0, the other a newer revision. The older one, no matter what BIOS flash had been attempted, never recognized any XP faster than a 1500. The other one worked fine with a Palomino 2100, but that was its top limit. It still worked with a 2600, but treated it as a 2100.

Neither one of them ever worked correctly with XP-M processors any faster than whatever an XP 1800 ran at (I can't recall what the older one did with a mobile XP). I ended up turning number two into a second rank loaner, with an old Thunderbird 1400 in it, and a fairly sizablke cooler to handle the waste heat. The oldest one suddenly died one day, after a short warning period of rapidly worsening instability.