Quote Originally Posted by LordEC911 View Post
Did you see the GTX680 frequency constantly moving in your tests?
There are reports that it can drop under the base clock during certain situations. I heard about this a few weeks back, maybe the newer drivers fixed this.
Where are these "reports"? I've never seen anything to indicate a game will lower the base clock and I had the clock speed monitor running through every benchmark I did.

As for the clock frequency, yes it does constantly move as the resources within the GPU shift however, most games "lock in" at a standard clock speed. Case and point, Dirt 3:



Quote Originally Posted by boxleitnerb View Post
I'm a bit confused about the turbo+OC

Hardwarecanucks and techpowerup both write that the OC offset leads to increased turbo headroom and activity and that the (guaranteed?) base clock cannot be increased. This would mean that depending on the circumstances you won't necessarily get the most from a given OC (i.e. 15% OC equals 15% performance increase).

However, the advertising slide for this feature shifts the whole curve further up, including the working point "base clock" and the subsequent turbo frequencies. That seems to imply that the new base clock=old base clock +offset is guaranteed. In some reviews OC gives proportionable performance benefits even in very demanding games, in some it does not.

Now what is the deal with that?
All right, this is a bit of a complicated answer so I will try to make it as short as possible.

First of all, increasing the offset WILL NOT guarantee that the GPU Boost will increase clock speeds to that level all the time. It will only do so when there is ample TDP / Power headroom which as we have been discussing is largely based off of the usage characteristics of every game / benchmark. A good example of this is Vince's 1800MHz overclock. If you look carefully at the Clock Speed, there are several instances where the GPU throttles down to drastically lower frequencies as it hits a power capacity wall.

This is why increasing the Power Target is so important; it basically gives you additional overhead to work with. However, the Power Target can only get you so far.

I'll give you and example:

Say you increase the Offset by 150MHz.

This means that games that normally Boosted to 1150MHZ would now be running at 1300MHz and games that ran at 1058MHz would essentially run at 1208MHz, hence the linear offset NVIDIA showed in their presentation slides.

HOWEVER, it will only increase clock to those levels if there is extra overhead for it to go above the default TDP. Hence why you need to increase the Power Target.

Without increasing the Power Target, there is a very good chance your Offset clock won't translate into actual in-game overclocks.


This is also why increasing ONLY the Power Target can lead to higher performance. Here's why:

Typically, the GPU will dynamically boost its clock speeds to stay as close to the default TDP ceiling as possible. Now what happens if you INCREASE the level of that ceiling? Well, the clock speeds have that much more headroom. I have seen situations where raising the Power Target to 120% will increase some in-game frequencies by 7-10%.


Hope that helps.