Im thinking gtx 960 woth TDP 120w? Would that leave oc room. The idea is i want a budget card like 960 so that it has enougth watts left for a oc to 4-4.5ghz althought with air cooler it wont be a big oc. When i upgrade the 960 in 2-3 years, then ill think about a bigger psu? Does that sound ok
I ran your specs through a power supply calculator. It seems that the Skylake CPUs are less power hungry than I thought. The calculator gave a
conservative estimate of 385 Watts of total power usage. That's a minimum, and as I said conservative. There are many factors which could increase that number very quickly.
Here is the website for the PSU calculator in case you want to fool around with it:
eXtreme Power Supply Calculator
As for overclocking... Based on the figures, you might have enough headroom for a stable OC if you don't OC your GPU at the same time. Going for 4.5 GHz is a little extreme, though. Especially on air. You might get 4 or 4.2 GHz without excessive heat, but YMMV. It's hard to say. You might be lucky and have a well binned CPU that will get you to 4.5, who knows?
Just remember the old adage:
"If you can't afford to replace it, you have no business overclocking it."