Athlon XP Barton - uhhhh yeah

I've googled and googled and I've seen that there is an issue with Bartons setting the FSB to 100MHz for some reason (or is it the BIOS? Nobody was terribly clear on whom I should blame). Right, so I assume this is a 2500+, with it's 11x multiplier, so that would mean an FSB of 166MHz. No biggie.

Wait, why is it saying "Athlon XP 1900+" on start-up?

Wait, why is the multiplier unlocked?

So yes, with that in mind, I am now completely unsure of what the hell is in this box. It's my brother's computer. We picked it up off a guy many months back. He was using it, from what I could tell, mostly as a basic home computer. We got it simply to run World of Warcraft for my junkie brother (which then returned my computer to me, thank the heavens). There was no documentation, and I am loathe to remove the HSF to investigate more thoroughly as I do not have any of the necessary tools or experience to do this safely and competantly. CPU-Z shows it only as an Athlon XP+ Barton with a (currently) 11x multiplier and 100MHz FSB, so not a lot of help.

I have changed the FSB to 166MHz to test it out. It POSTs as a 2500+, but then after the windows boot screen it simply hangs on black with the mouse cursor. There is peripheral power and the like, but that's all - black screen, mouse cursor, the hum of CPU fans. The same occurs at 133MHz, which is as slow as the Bartons came for FSB.

For analysis, I've got the basics of the CPU-Z file here for you.


Processor(s)

Number of processors 1
Number of cores 1 per processor
Number of threads 1 (max 1) per processor
Name AMD Athlon XP
Code Name Barton
Specification AMD Athlon(tm) XP
Package Socket A (462)
Family/Model/Stepping 6.A.0
Extended Family/Model 7.A
Core Stepping
Technology 0.13 um
Core Speed 1100.2 MHz
Multiplier x Bus speed 11.0 x 100.0 MHz
Rated Bus speed 200.0 MHz
Instruction sets MMX (+), 3DNow! (+), SSE
L1 Data cache 64 KBytes, 2-way set associative, 64-byte line size
L1 Instruction cache 64 KBytes, 2-way set associative, 64-byte line size
L2 cache 512 KBytes, 16-way set associative, 64-byte line size


Chipset & Memory

Northbridge VIA KT400A rev. 80
Southbridge VIA VT8235 rev. 00
Memory Type DDR
Memory Size 1536 MBytes
Memory Frequency 166.7 MHz (FSB + 66 MHz)
DRAM Interleave 4-way
CAS# Latency (tCL) 2.5 clocks
RAS# to CAS# (tRDC) 4 clocks
RAS# Precharge (tRP) 4 clocks
Cycle Time (tRAS) 7 clocks


System

System Manufacturer MSI
System Name MS-6712
System S/N 00000000
Mainboard Vendor MSI
Mainboard Model MS-6712
BIOS Vendor American Megatrends Inc.
BIOS Version Version 07.00T
BIOS Date 04/02/01


Memory SPD

Module 1 DDR, PC3200 (200 MHz), 512 MBytes, Apacer Technology
Module 2 DDR, PC3200 (200 MHz), 512 MBytes, Kingston
Module 3 DDR, PC3200 (200 MHz), 512 MBytes, Apacer Technology


Software

Windows Version Microsoft Windows XP Professional Service Pack 1 (Build 2600)
DirectX Version 9.0c




Can someone please tell me what on earth is going wrong here?