I am using two GTX 570 in SLI configuration to play games on a 30" Dell monitor at 2560x1600. My understanding is that frames are limited to the refresh rate of the monitor - 60hz. Thus, is there a benefit to overclocking the cards if I'm already maxing out 60fps in the games I play?
Short answer - probably not. As long as you can maintain at least 30fps in the most demanding scenes, you won't notice a difference either way. If you're averaging at least 60fps in whatever settings you use, I wouldn't bother with the added heat and fan noise you would cause for a few percent gain.
30 fps is generally where your eyes will really start to detect that the framerate has dropped in most fast paced games if its a quick drop (particle effects from an explosion or something similar). Extended periods of 30fps you will definitely notice. Reviews typically look at fps because its the best and most easily quantified representation of performance with settings maxed out.
Depending on the games and settings you are playing at that resolution, staying capped at 60 fps at all times probably is not going to happen even with your two very powerful cards. Even in situations where your average fps is right around 60, overclocking can help increase your minimum framerates at chokepoints in games where there's a lot happening on-screen.
Really the question you might want to ask is "why not overclock?" or perhaps "to what extent should I overclock?" If you can increase your frequencies (and performance) in a stable manner, you're getting more value out of your purchase. Especially without increasing voltage.
If you are fully happy with your performance and don't feel like you are experiencing slowdowns at any point, there's nothing wrong with leaving everything at stock settings.
Thanks, beltzy. I don't want my system to run too hot. I am already using 6SSDs along with 6 HDs, 2 GTX 570s, and an i52500k oc'd to 4.5ghz. Despite my best efforts, I can't get it stable at 4.5ghz without using at least 1.366Vcore. Thus, it idles at 36C and tops at 55C under load. I think if I oc'd the GTXs too much, especially with more voltage, I might get above 60C in the system and though I've seen higher on others, I'd like to keep mine low.
2. Average frame rates and minimum frame rates are two different things. Crysis played great maxed out on my son's box .....except for the part in the airport tower where minimum frame rates dropped to annoying levels.
As for the OC'ing .....
4.6 Ghz is reasonably obtainable on > 50% of 2500k; 10% will do 4.8 Ghz
The 570's is the best of the 5xx series if left at it's stock settings. It's VRM is perhaps less beefy than we'd all like as it doesn't tolerate increased voltages very well. The 560 Ti's (900MHz factory OC versions w/ the oversize coolers) on the other hand are very robust when it comes to OC'ing and scale a bit better. Twin 900 MHz 560 Ti's will garner 862 fps in SLI in Guru3D's test suite while the 570's at stock garner 873 fps.
Still, unless you are going to exceed manufacturer's voltage limits, the 570 is a fine card. You can crank it up as long as your case cooling can handle it just be careful not to exceed those stipulated voltage limits as there's not much headroom in the 570.