it could be the PSU, as its not a quality one. XP has a feature that causes it to auto restart when something goes wrong. this can be bad, as u wont see the blue screen of death to tell u the problem. Go to system properties, go to advanced, look for startup and recovery and click on settings. uner system failure, uncheck the box next to auto restart. then when u get ur blue screen of death, copy and paste what it says here.
-AMD Athlon 64 3200+ Winchestor
-MSI K8N Neo4-F
-Sapphire Radeon X850 XT
-2x 1024 Corsair XMS Pro
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