Please remember that any mention of competitors, hinting at competitors or offering to provide details of competitors will result in an account suspension. The full rules can be found under the 'Terms and Rules' link in the bottom right corner of your screen. Just don't mention competitors in any way, shape or form and you'll be OK.
I doubt they have a dodgy batch as they must have sold loads of them, but quite a few people are having problems.
The PSU normally gets blamed but I've tried mine on two and it made no difference.
Here's some threads:
http://forums.overclockers.co.uk/showthread.php?t=17792319&highlight=ocuk+1950pro
http://forums.overclockers.co.uk/showthread.php?t=17789632&highlight=ocuk+1950pro
http://forums.overclockers.co.uk/showthread.php?t=17773025
OCUK said the X1950 Pro was OK in their system and have sent it back again!
I'll try it again when it arrives back on Monday, I've now got a Hiper 530W PSU instead of the Antec 350W one (which had worked fine for months) just in case this was the problem, thought I don't expect this to be the case from what I've read.
If it still doesn't work I'll be *really* *****d off -- I've replaced both PSU and motherboard trying to fix the apparent short-circuit which has cost me over £90, not to mention a couple of wasted days frigging around with all this...