I've put up with this problem since early 2006 believe it or not but it seems now its gotten worse and doesn't only happen on cold boots but even when its had power for sometime, it used to be once a day when i first powered it straight up, unless i left the power to the wall socket on for 10 to 30 minutes (pc not actually being switched on at this point), i have a feeling its the capacitors somewhere as this would explain why that worked but its gotten worse now so im wondering what i should do? 
I was thinking of getting a psu but i don't know whats best and if im to get one i need it to be future proof for next year when i get a new high end system.

I was thinking of getting a psu but i don't know whats best and if im to get one i need it to be future proof for next year when i get a new high end system.