Thanks Richard, I will try that next.
The RAM sticks, despite being ordered from the same place within a week of each other, seem to be different manufacturers:
A-data & TwinMOS
Is that a problem?
Also, looking at PSUs, will this one do the job? -
Mercury PSU 400 Watt AMD/Intel P4
Product Description -
High quality 400 Watt PFC power supply manufactured by Mercury. Intel P4 & AMD Approved, Complies with ATX Rev 2.03, 12v Fan Fitted, Low Noise, over-voltage protection, CE , FCC, TUV, UL Approved, Dimensions 150L x 86W x 140H mm.