How much will overclocking improve my gaming performance?

Maybe 15% or so in games. You can take that i5 right up to 4.0GHz with the stock cooler, just by changing the multiplier to x40.

Usually an overclocked gpu will give more frames than an overclocked CPU.

I have a 4670K and overclocked it temporarily from 3.6 to 4.4 and did "before and after" tests on 3 games
1920x1080 - everything I could on max (AA, AF, shadows etc)

The GPU was a MSI Twin Frozr 780 that runs just a little over Nvidias stock. But other than the the GPU is not OC/d
16gigs of 1600 RAM on an MSI Z87-G45 gaming mobo.

Crysis 3. CPU standard avg 48 max 63
Crysis 3 CPU@4.4 overclock average 52 max 67

Guild Wars 2 CPU standard avg 88 max 121
Guild Wars 2 @4.4 overclock avg 99 max 135

Skyrim CPU standard avg 104 max 120
Skyrim @4.4 overclock avg 107 max 120

(the 120 might be a hard limit on Skyrim - not sure about that)

Overall Guild Wars 2 was the only one to see significant benefit from the overclock. I'm happy gaming normally at 60
I know many love to see 3 figure FPS scores - but they really don't matter to me my main screen is capped at 60 anyway so I have to turn Vsync off and let the GPU waste a ton of time rendering frames that never get shown once I go over 60 but it's important to some.

Thing is GW2 was mondo high to begin with. The OC made a ludicrously high figure just higher still IMO. In the other games where I might have liked a benefit the calculated increase was tiny - the difference to gameplay quality was precisely and exactly ZERO for me (but then I'm middle aged - youngsters might see the difference.. or at least have the youthful presence of mind to imagine a difference where there is none)

Likewise Skyrim - even with the Hi res GFX packs installed really isn't that hard on a half decent PC. (it's coded to run on the Xbox 360 - almost 8 year old architecture) I wish I'd had time to test Far Cry 3 and the latest Tomb Raider games with the real "hair" physics, but I don't have the time.

All in all, OCing is something I do at the end of a chips life when games are pushing the CPU limit and the software out there really NEEDS the extra "oomph" I had my 2500K at 4.2 for the last 6 months before I gave it to my son, but spent the previous 2+ years at stock. It still works fine now. Not a single game it can't handle.

I won't make a general conclusion - but for me - overclocking is not something I've found particularly worthwhile in any real world sense. The caveat being to get an extra 12-18 months out of an aging chip to keep up with games that push it late in it's life cycle. For most modern i3, i5 or i7 processors and even the AMD equivs?

Hardly worth it. but that's just me.

Paul Rone-Clarke

[EDIT]
Wrong Crysis figures. The latest Nvidia drivers increased the FPS quite substantially (Late 2013) Crysis was particularly affected so add about 8 FPS to the average and max on that game

i ran my system through Metro last light benchmark at stock settings.

SLI 660 ti
FX 8350 (4.0 Ghz)
8Gb 1600 RAM Cas 8

I maxed all values, left off SSV and Physx and ran at 1920x1080. I got an average of 59 FPS.

Then i started to overclock. 4.2ghz with multiplier got me the exact same. 4.5ghz with the Bus speeds and RAM OCed as well...got me 59 FPS as well. I decided that overclocking, at least in the current game im playing, didnt matter at all and I would rather keep my CPU at the cool idle temp of 19C (Corsair H60)