Overclocking to squeeze performance out for gaming

Mainly I want to play Far cry 4 on ultra setting

I have a 7950 now overclocked to 1000 MHz
Memory at 1560 MHz
2500k not over clocked as yet.

Is this sufficient to play farcry 4 at reasonable frame rate ie over 40fps at 1920 x 1200?

Not sure about ultra I would try high, some of the ultra settings can be a bit punishing and not really worth it. E.g I tried ultra on the vegetation setting and to me it actually looked worse, slightly more detailed but maybe too sharp when looked at but not noticeable when moving around. I run a mixture of high/ultra on a gtx970 for 1080p although I'm running with vsync so aiming to not dip below 60.

Supposedly the 2500k is an easy overclocker so probably a good idea to give the multiplier a bump, not my field though. That's more to prevent fps drops than improve average fps.

I think from a value point of view, if you could just let us know what cooler you have, and what PSU you have, and which mobo, we can advise on overclocking that K designation CPU.

It's got an unlocked multiplier and most would agree it's safe to add a few notches to it's multiplier for day to day use, if you've got the better cooling for that. I would be looking at doing that unless you really want to do a resale in the future and at that stage offer it as non overclocked.

Good job on the memory so far, that must have been an (effective) 1333 megahz kit?
I personally can't tell you or not if that advice will 'matter ' for Far Cry 4, it may depend on if you play with vsync (thought it may just not, equally).

A stock 2500k with a 7950 should do FC4 on High at that res fine; it's not too hard on the CPU, it actually runs fine at that res on an 13 3220/7850 stock (~65% CPU) - even playable at almost full Ultra.