Nehalem Revolution: Intel’s Core i7 Processor Complete Review

Testing Methodology and System Setup

With a completely new processor architecture and chipset, there are obviously a TON of permutations that can and should tested to get a proper feel for the overall performance and efficiency of the new CPU.  With Nehalem in particular we want to look at several things:

• Overall system performance
• Multi-threaded application performance
• Single threaded application performance
• Performance-per-watt indicators
• Performance-per-clock indicators
• HyperThreading performance
• Clock-for-clock generation comparison: Core 2 vs Core i7
• How AMD’s Phenom X4 fits in
  

As you can tell, that is a LOT of information to gather but I think we have done a good collecting it all and putting it in place for you here. 

In our review kit, Intel sent us engineering samples of the Core i7-965 Extreme Edition and the Core i7-920 processors.  I was able to simulate the Core i7-940 processor but downclocking the Core i7-965 from 3.20 GHz with a 6.4 GT/s bus to 2.93 GHz with a 4.8 GT/s bus – all easily accomplished using features in the Intel X58 “Smackover” motherboard BIOS. 

To compare against the new Core i7 processors, I selected a few Core 2 CPUs that I felt represented the best overall competition.  First, I obviously picked the Core 2 Extreme QX9770 as it is the fastest quad-core processor Intel made up until this release; it is the perfect competition for the new Core i7-965 Extreme Edition.  Next I wanted to get a Core 2 processor that was on the same price level as the Core i7-940 that is estimated to come in at $562 or so.  For that I went with the highest-end Core 2 Quad available, the Q9650 that runs at 3.0 GHz on a 1333 MHz FSB: it sells for about $550.  Finally, I knew that I needed a dual core option in the testing so that users that have such a system can see what their upgrade potential would be.  For that I found a Core 2 E8500 Wolfdale processor selling for about $200 today.  I also threw in results from an AMD Phenom X4 9950 Black Edition CPU that sells for about $185 today – the top end consumer part that AMD actually offers.

The Turbo Mode that the new Nehalem core offers puts another spin on our testing configurations by requiring us to test each CPU with the feature enabled and disabled.  I will explain a lot more about how the Turbo Mode option affects your clock rates and overclocking performance later in the review, but suffice it so that in my experiences Turbo Mode, as it is set at by default, will raise your clock rate by 1 multiplier during CPU loaded times.  We saw our 3.2 GHz Core i7-965 EE run at 3.33 GHz during load, the 2.93 GHz i7-940 run 3.06 GHz and the 2.67 GHz i7-920 run at 2.80 GHz whenever we were stressing the processor.  It might seem a little gimmicky when worded like that, after all if the processor can run at 133 MHz faster when loaded, why not much MAKE it that fast of a processor to begin with? I’ll debate this more on the overclocking page of the review.


Another key point in the testing configuration has to do with the memory configurations.  Remember that while the new Nehalem-based Core i7 processors have a triple-channel memory controller, the existing Core 2 and Phenom processors use a dual-channel controller.  That means that to get optimal performance on the Core i7 parts we have to install memory in triplets while we need memory in pairs for the Core 2 and Phenom.  So my options were really like this:

• 3 x 1GB (3GB total) DDR3 on Core i7 versus 2 x 1GB (2GB total) DDR3/2 on Core 2 and Phenom
• OR
• 3 x 2GB (6GB total) DDR3 on Core i7 versus 2 x 2GB (4GB total) DDR3/2 on Core 2 and Phenom

I decided to go with the latter option as it seemed the most realistic and forward looking.  I also believe that by raising the memory limits to 6GB vs 4GB rather than 3GB vs 2GB, the differences in performance that total memory capacity would be lessened. 


Since we had to start from scratch with all of these testing systems, I decided to freshen up the benchmark suite as well.  We are still including much of our previous testing suite but have updated it all to the latest available versions and have added in a few new ones as well.  A fluid dynamics simulation was added in the form of Euler3D, VirtualDub has been updated to include SSE2 and SSE4 results, a new rendering test known as Blender has entered the fray and one of my new favorite “toy” applications called Microsoft Image Composite Editor was thrown in there as well.  MS ICE is a program that allows you to take any number of related images and “stitch” them together to create a single panoramic photo.

Our gaming tests for the CPU portion of this launch are focused on low resolution, high speed, CPU-bound gaming scenarios.  3DMark Vantage was of course included but we have added in World in Conflict, Crysis and the newly released Far Cry 2. 

Overall I think you will find the collection of 19 benchmarks applications with 35 overall tests to be quite complete. 

As a side note, don’t worry: we plan on having to more Core i7 performance articles ready this week including a GPU scaling article that will look at SLI and CrossFire scaling performance between the Core 2 QX9770 and the Core i7-965 EE.  We will also have a detailed look at our first set of ASUS X58 motherboards – the P6T Deluxe and the Rampage 2 Extreme both of which have a LOT to offer the enthusiast user.