Real World Gameplay CPU Scaling

Four processors; Intel Core i7 920, Intel Core 2 QX9650, AMD Phenom II X4 810, & AMD Phenom II X3 720 BE. Seven games. REAL WORLD GAMEPLAY at stock clocks and all overclocked to 3.6GHz, head to head, & apples to apples.


CPUs are an important part of gaming, it is impossible currently to play a computer game without one no matter how much you are told these processors are becoming a diminishing portion of your gaming experience. We have recently seen the Infernal Engine scale gameplay physics, not effects physics, across 8 threads of an Intel Core i7 processor. We’ve been seeing CPUs trending towards improving multi-core designs, adding more cores, and deepening pipelines instead of simply being focused on clock speed. Does all this matter to the gamer? If you take a look at the video below, you will see the CPU being leveraged to impact gameplay beyond "eye candy," and the Ghost Busters’ gameplay below never leverages beyond 2 physical cores on a Core 2 Quad.

Our Focus and Goals for This Article

In this article we are going to take some popular and new CPUs today and perform our ritual of gameplay evaluation to find the highest playable settings with each CPU. We are also going to provide good old apples-to-apples gameplay in each title to compare clock-for-clock performance and how much overclocking each CPU gains in Frames Per Second (FPS). We will conclude with a summary of gameplay and then our conclusions based on the data collected.

We are going to answer such questions as: Is the Core i7 920 really faster in games than a Core 2 Quad? Is there really any difference in gameplay performance between the triple-core AMD Phenom II X3 720 BE compared to the quad-core AMD Phenom II X4 810? Intel or AMD? Clock speed vs. multi-core? Finally, what value does each CPU bring, and can overclocking help?

CPU Lineup

We are going to be covering four CPUs at both their default frequencies and an overclocked frequency of 3.6GHz. We have done a lot of testing with the new Core i7 series, specifically the i7 920. Intel Core i7 Synthetic testing can be found -HERE- while Core i7 Application testing can be found -HERE- and finally Core i7 Gaming testing can be found -HERE-. You will also find specific testing on Overclocking, Heat, and Power -HERE- and -HERE-. We will be using the Core i7 920 at its default frequency of 2.66GHz and overclocking it to 3.6GHz as well.

We will also be using an AMD Phenom II X4 810 and AMD Phenom II X3 720 BE, both on a DDR3 platform. The AMD Phenom II X4 810 is a quad-core CPU running at 2.6GHz by default and we will overclock it to 3.6GHz as well. The AMD Phenom II X3 720 BE is a triple-core CPU and runs at 2.8GHz by default and will also overclock it to 3.6GHz. You can read our coverage of the new AMD Phenom II -HERE- and -HERE- on a DDR3 platform.

We will also be using an Intel Core 2 QX9650 at its default frequency of 3GHz and overclocking it to 3.66GHz. This will provide a comparison for the i7 920, to see if the new i7 core is faster or not compared to the Core 2 Quad in real-world gameplay.

How To Ensure a CPU Test

Given that this is a comparison of CPUs we must take the video card out of the equation as much as possible, meaning that we did not want to end up with GPU-limited gameplay scenarios. With the ever-evolving line of video cards this is easy to do for the most part. We have opted to use AMD Radeon HD 4870 X2 CrossFireX. That is, we have installed two Radeon HD 4870 X2 video cards into each system and enabled CrossFireX for quad-GPU acceleration. The Radeon HD 4870 X2 provides 1GB of framebuffer memory to each GPU and provides the shader power necessary to run each game at very high settings. With a powerful video combination like this it will be interesting to see which CPUs allow it to achieve its full potential.

Note there are two games which do not support quad-GPU acceleration in CrossFireX. Flight Simulator X will only run on one GPU, despite having two video cards installed. Therefore in this game we removed one of the 4870 X2 cards and simply ran with one 4870 X2 installed. Flight Simulator X only uses a single GPU on that single card. In Grand Theft Auto IV the game is limited to using two-GPUs for acceleration. So once again we took out one of the 4870 X2’s and left the other installed of which the game will use both GPUs on that card. AMD has informed us that these limitations are currently in place because both games are so CPU dependent that enabling CrossFire beyond two-GPUs in GTA4 and one-GPU in FSX actually hurts the overall performance; we will see for ourselves. Every other game used fully supports quad-GPU CrossFireX.

We can easily use the Radeon HD 4870 X2 CrossFireX configuration as our video card control amongst every CPU because of our platform setup. For the Intel Core i7 920 we are using an Intel X58 based chipset which fully supports CrossFireX. For the Intel Core 2 QX9650 we are using an Intel X48 based motherboard which also supports CrossFireX. Finally, the two AMD CPUs are on an AM3 790FX board which natively supports CrossFireX. All boards run DDR3 memory.

How We Test Overview

On each gameplay page we will start with our real-world gameplay highest playable settings evaluation. We will start with one table and graph showing the highest playable settings at default frequencies, then we will show another table and graph below it with all CPUs overclocked. Below that section will be the apples-to-apples testing which keeps all the in-game settings and resolution the same. We have opted to disable AA in the apples-to-apples test to further remove GPU limitations making game more CPU dependent. So our first testing set is the best quality actual real world gameplay that could be supported by the system as you would likely find if playing the game yourself. Second, the A2A testing is more of a "benchmark" although we still use gameplay testing, but with replicated settings and no-AA.