KT133 Chipsets and Athlon XP CPU's

A couple of us have put Athlon 1600+ XP CPU's (Palimino core)in our old Abit KT7 boards (with KT133 (non A) chipsets. First, they ran fine at 1050mhz. That is the default for a 1600+ XP running on a 100mhz fsb. The multiplier is locked at 10.5xFSB. On an XP approved machine with a 133mhz FSB it normally runs at 1400mhz (10.5x133). But since the older KT133 chipsets 133mhz fsb doesn't work like it was supposed to, we're limited to a base 100mhz fsb. First attempt was to unlock the cpu and try and change the multiplier in the bios. That did not work. I could take the multiplier down now, but not up. This was with the 64 bios. It may be different with other versions. You can try it if want. ymmv. So then I went and scraped the L1 bridges back off the cpu to lock it back and proceeded to change the locked value on the cpu. This process was MUCH easier than it had been to put the 5 bridges across the L1 contacts. To be a little conserviative, I chose to lock it at 16x. This would give me a 1600mhz machine or the equivalent of a 1900+ cpu. And I new that I could get the FSB to run at 116, so that's another 256mhz I could go up if I wanted to, or the equivalent of a 2300+, which I was pretty sure it wouldn't do. Warning. DOn't cut to deep when cutting traces. It doesn't take much. I made a big gouge in the first one I did. Didn't matter, but the trace is just underneath the surface. you can see it if you look hard enough. All done, install it and boot. The darn thing comes up running at 1840mhz. Yes 1840, and it's fast as h*ll, but freezes shortly after booting. I reboot and get back into the bios. The multiplier is still at 10.5 from when I had it set earlier, so I change it to 1200 and above and reboot. This time it boots up at 1600 and everything looks ok. So I reboot again this time it comes up at 1650, and all boots [ast this come up at 1650mhz. Hmm.. Oh, well. So I play with the FSB just a little and get it running stable at 1766mhz. All's fine. I set it back down to 100mhz fsb and let it run a few hours. No problems. Go to bed happy about 4AM.:-) Next day I move the cpu into the machine I normally use (another KT7-raid) and boot it. This time setting the bios to =>1300 or something like that before I shut it down with the old cpu in it. Stange, but although both have the same bios, the other machine showed only 12 and above. Nothing with 1300 in it. So reboot again expecting to see 1600mhz again. Wrong. It's now at 1650mhz. Basically did the same thing the other machine did. Started first time at 1600, then jumped to 1650. And now the 1300 reference in the bios is gone, just like the other machine. So, just let me say that there are some bios issues at play here. As I said, both these machines have the 64 bios from Nov. 2001 I think. With other bios things might be different. Fast Eddy set his to 1600 too and it came up defaulted to 1700. I'm pretty sure he had a different bios version then I do. I'm not worried about it, just thought I'd let you know in case you see some strange behavior. Almost forgot. Heres' some links to read if your considering using an XP on a KT133 chipset machine. Shouldn't matter who made it.
These links should help you with modifying the cpu and determining the how to modify the multiplier. 

http://www4.tomshardware.com/howto/01q4/011112/index.html
http://www.ocinside.de/
http://forums.sudhian.com/messageview.cfm?catid=32&threadid=19593&STARTPAGE=1

Disclaimer: Do at your own risk.

Here's my cpu info.

processor : 0
vendor_id : AuthenticAMD
cpu family : 6
model : 6
model name : AMD Athlon(tm) XP
stepping : 2
cpu MHz : 1801.487
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow
bogomips : 3591.37

Udate: 04/09/03

Installed a 2100+ Tbred B core cpu the other day. It does not require any mods to operate at the max potential. As much as I hate the phrase, it's plug and play up to `2400MHz. See Multipler cross reference for multiplier settings up to 24x. Here's what I got. ymmv.

processor    : 0
vendor_id    : AuthenticAMD
cpu family    : 6
model        : 8
model name    : Unknown CPU Type
stepping    : 1
cpu MHz        : 2400.188
cache size    : 256 KB
fdiv_bug    : no
hlt_bug        : no
f00f_bug    : no
coma_bug    : no
fpu        : yes
fpu_exception    : yes
cpuid level    : 1
wp        : yes
flags        : fpu vme de tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow
bogomips    : 4784.12

Update 12/05/03: CPU's with a date code of 0339 and later are being multiplier locked internally by AMD. Since the multiplier can't be changed via any method at this time on these locked cpu's, you will only be able to run the cpu at default multiplier times the max FSB speed you can get from your motherboard.