My Grandad will NOT listen.
He is using what must be a 5-6 year old generic PSU, I'd guess around 300-500W... He's been using an 8600GT, 9800GT, now he's using a GTS250 and if my uncle upgrades no doubt he will then cram the 5770 into it and it WILL blow the PSU up. He will not listen to me that he shouldn't be using a generic POS PSU...
Well both the 9800GT and GTS250 he's used are both PNY low power versions that don't require anything extra from the 12v rail.