Hi!
Sory for my english, I write from Poland.

I've tested my RAM with Memtest86 and there are some errors
(Moving blocks test #5)

This is the second RAM, after many system freezes
I exchanged it to new one and the error is still there.

I've also tried to change PSU from my 300W to 380W
and nothing happened.

The errors disappeared when I changed DDR clock
from 400MHz (200) into 366MHz (166).

What can be wrong?

Processor:
Family AMD Sempron™ Processor 3000+
Architecture 64-bit
Internal Clock 1.8 GHz
Internal Clock Maximum 3.7 GHz
External Clock 200.0 MHz

Motherboard:
ASUS K8N4-E Deluxe
N-Force 4
socket 754,
PCI-Express

Display device:
ABIT Radeon RX600 PCI-Express, 128 MB

Memory:
2 x 512MB 400 KingMax

PSU:
HuntKey 300W ATX12V 1.1 or NeoTec 380W

OS:
Windows XP Pro. SP2 (32 bit)

I got the newest BIOS update (rev. 1007)