Where do I start

[#1]

managed to source a video card from an old computer but no luck
New power supply arrived today but...... still no luck so rather than mess about and spend more cash I will be ordering a new computer
Thanks to those who offered suggestions on things I might try. 

[#2]

One last thing to try. 
Download and burn a copy of MemTest86+, then run your PC from the bootable CD or USB stick, and see if that identifies any problem.

[#3]

SOLVED......see chit chat

[#4]

I did thank you

[#5]

Have you replaced the motherboard battery?
I had a mate with this problem years ago and we tried everything else but it continued crashing for no apparent reason. Finally we replaced the mobo battery.. guess what? No more crashes!

[#6]

Hope its not the soldered type of CMOS battery