NVIDIA GeForce GTX 980 Overclocking Video Card Review

The new NVIDIA GeForce GTX 980 makes overclocking GPUs a ton of fun again. Its extremely high clock rates achieved when you turn the right dials and sliders result in real world gaming advantages. We will compare it to a GeForce GTX 780 Ti and Radeon R9 290X; all overclocked head-to-head.

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Overclocking the NVIDIA GeForce GTX 980

Since this is just a reference card we can use whatever third party overclocking program we like. We chose to use the latest version of MSI Afterburner since it allows us to utilize an on screen display in-game where we can monitor all aspects of GPU frequency and statistics. This allows us to make sure the clock speeds are consistent over long periods of gaming. We can also see what games show different clock speeds.

Our goal in overclocking is to find the overclock that is consistent and sustainable over long periods of time gaming. The last thing you want is the clock speed to start throttling after thirty minutes of gaming, or more. Therefore, we play games for lengthy periods of time, just to make sure the clock speed never changes, or if it does, by how much, and then report that. BTW, we always focus on the real-time in-game GPU frequency achieved, not the Base or Boost clock which is misleading. We want to know what the actual clock speeds are, else how can we tell if its throttling?


Re-Think Overclocking

Normally in our past evaluations we have divided the overclocking page up into two sections. We first start by showing you what overclock we were able to achieve without touching the GPU voltage. Then, in our second section we show you the overclock with added voltage. In this way you can compare what advantage extra voltage had. We are going to have to re-think how we achieve a highest stable overclock.

Overclocking GPUs has changed since NVIDIA launched GPU Boost in its video cards, and AMD released the very hot and power hungry R9 290X. How we think about voltage has changed. Most people overclocking have come to this realization, as have we when we overclock video cards. However, we haven't really explained it well, and we need to better state this information with the release of the GeForce GTX 970 and GeForce GTX 980.

In the past of video card overclocking (before GPU Boost and Power Tune) one was content to put priority and emphasis on voltage in order to garner the highest overclock, granted that cooling was enough. However, with NVIDIA's current implementation of GPU Boost and AMD's Power Tune there are limits on a video cards TDP or power limit. These power limits limit the GPUs clock speed based on hardware and software monitoring in place by NVIDIA and AMD.

If you read back on our MSI GeForce GTX 970 GAMING evaluation you will find we hit the power limit wall pretty dead on. Once we hit this wall, the clock frequency would start decreasing itself. We had to find the proper balance of voltage and clock frequency boosting until we found a level of consistent frequency that did not throttle and did not exceed the TDP or power limits in place.

Unfortunately, the GTX 970 has a low 10% power limit adjustment. This overall caps the performance we can get out of overclocking. No matter how much voltage we add, exceeding the TDP downclocks the clock speed. In fact, adding too much voltage, even without changing the clock speed can in fact make the GPU hit that TDP wall faster, lessening your potential to overclock. The power limit is the overall limiting factor for overclocking the GTX 970, we think the GPU could overclock even higher if it didn't have this limit. Though it got a high overclock anyway, we feel there is more potential in that GPU.

This is exactly the same result we had with the GeForce GTX 980. We could in fact overvolt the GTX 980 as high as +87 making for a total of 1.243v compared to the 1.218v default. The problem was, doing this meant we actually had LESS headroom to overclock.

The reason being is that by overvolting to the maximum voltage made the GPU hit its TDP wall a lot faster when we raised the clock speed. Power goes up, you hit the TDP wall faster, even with the Power Limit slider maxed out. So what seems reverse thinking, actually keeping the voltage at its default voltage resulted in a higher overclock than overvolting the GPU!! That's right, NOT touching the voltage resulted in an overall higher long term in-game stable overclock, by 64MHz!

Because of this we are just going to show you the highest overclock we achieved, which happens to be without changing the voltage.


Maximum Overclock

First let's start with what the video card runs at by default. The Base Clock is 1126MHz and the Boost Clock is 1216MHz. The actual in-game frequency while gaming turns out to be a consistent 1240MHz.

However, we did find something interesting. By raising the fan speed to 100% and raising the Power Limit slider the GPU would actually run consistently at 1252MHz. This could mean custom cards might have higher actual in-game frequencies with better cooling. Since we want to start from the default frequency, with default power and fan settings, we will go with 1240MHz as the actual frequency we are starting from before overclocking. We checked in all games that this frequency was consistent after long periods of gaming.

The Power Limit slider goes to a maximum of +125, or 25% over TDP. That at least is a little more headroom than the GeForce GTX 970. Again, we could have maxed out the voltage to +87, but we found the highest overclock came from leaving the voltage alone and letting GPU Boost do its thing automatically.

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Our final overclock turned out to be +250 Core Clock offset and +500 memory offset. This results in a Base Clock of 1377MHz and a Boost Clock of 1466MHz. However, the real-time in-game frequency is actually 1516MHz!

However, there is a disclaimer with this overclock. There were some games that throttled between 1497MHz - 1516MHz while gaming. Worse case scenario, we saw the clock speed run at 1497MHz, but then it could and would dynamically change as we played. In certain parts of the game it would be 1497MHz, in other parts it would be 1516MHz depending on the load.

Throughout the entirety of two games it remained consistent at 1516MHz without changing at all. However in a couple of other games it did dynamically change between 1497MHz and 1516MHz. Therefore, our overclocking range is actually 1497MHz to 1516MHz, depending on the game and the game situation. We never saw it drop below 1497MHz, unless we raised the voltage.

The default voltage to achieve this was 1.218v. If we raised the voltage to 1.243v the maximum overclock we could achieve was only 1452MHz. We could not get the GPU over 1452MHz with the GPU voltage maxed out. Anything above that would throttle the GPU back to 1452MHz. Therefore actually keeping the voltage lower, at its default 1.218v allowed a 64MHz higher overclock.

We achieved an 8GHz clock on the memory. This is a full 1GHz overclock from the default of 7GHz.

Our final overclock was: 1516MHz/8GHz. This is a 276MHz overclock. Yet, we do feel there is more headroom in this GPU just like the GTX 970. We are only held back by the TDP/Power Limit wall. Imagine no power limits, and being able to raise the voltage, 1.6GHz may not be out of the realm of possibility. Remember, this is just a reference video card, with reference cooler, and we got 1516MHz out of it without changing the voltage. Simply outrageous, in a good way.