The motherboard im looking at is the Z68X-UD3H-B3 and it requires ATX 8-pin 12V (2x4) connection. I just got a 650watt PSU from my mate and it only has one 4 pin ATX 12V power connector. Would it be fine to plug the 4-pin from the PSU into the mobo and also buy a molex to 4-pin adapter and connect it up next to the other one? If all else fails will get a new power supply!
I will be running the core i5 2500K with a decent graphics card
It depends on how the motherboard and PSU are configured.
(1) If the molex and the 4pin ATX are on the same rail then No problem and 92) does not mater; However on multrail PSUs that is not normally the case.
(2) It is possible that all of the Positive pins are tied together on the board. You would need to verify that this is not the case (ie with a DVM measure the ohms beween the Positive pins - Put black meter lead to first red pin then with the black lead measure to the other 3 red pins, if 0 ohms they are all shorted. The problem then becomes that this will short one +12 V rail to another +12 V Rail, A No-No.
On 4 vs 8 pin atx power. 4 pin is designed for upto 125 watt CPUs, 8 pin is for > 125 Watts. The i5 is a 95 watt and will exceed that when OCed, but probably not go above the 125 Watts unless you are increasing vcore close to max. Primarily this is a factor of the IR drop accross the pins, not a limitation of the +12V rail or the wires.
Always an exception, MB may impliment seperate feed to the Regulaters (Phases) inwhich case for an OC you need to use all 8 pins. As stated you need a DVM to verify.
Well im pretty sure i have 2 rails on my PSU but even then i dont have a DVM to measure. Plus im not sure when u say "put black meter lead to first red pin"... red pin from what?
So the safest option would be no adapter, just the 4-pin... and then the next option is the splitter. Is it even worth bothering to get an adapter because as u say the i5 only needs 95watt and the 4 pin alone would be sufficient?
The 95 watts is for stock and the four cours loaded, if you OC then the Power goes up.
My best guess is that as longe as you only increase Vcore a slight bit and say only go to 4.6 Gigs for an OC you are probably OK.
My self, I'd play it safe and get the $6.00 adaptor that I provided a link to. With that You can forget the DVM measurements..