Intel Core 2 Quad Q8400 CPU Review

It was not too long ago that the web was buzzing with dual-core versus quad-core debates. Sides were taken and lines were drawn. At that time, one of the main arguments against quad-core processors was their high asking price. But as time passed and manufacturing refinements were made, costs steadily decreased and quad-cores found their way into the more mainstream market segments. And before you knew it, a price war was imminent.

Intel and AMD have been going at one another for years. With AMD unable to compete well at the ultra high-end of the market, however, their focus shifted towards the mainstream market segments. As always, Intel responded and their most recent salvo comes in the form the affordable Core 2 Quad Q8400 processor. Since the Q9400, a 2.66GHz Yorkfield quad-core, was already on the market, why did Intel feel the need to release another, affordable quad-core model? One reason could be to increase yield and utilize dies that would otherwise be discarded. Another reason would be to position another product at the same price point as AMD's. Whatever the case may be, competition is always good for the consumer as it usually drives prices lower and provides more options to choose from. With that in mind, let's take a look at the Intel Core 2 Quad8400 to see if it's worthy of consideration for your next build...

Intel Core 2 Quad Q8400 Close Up

Intel Core 2 Quad Q8400 Processor
Specifications & Features
sSPEC number
Core Frequency
System Bus Frequency
Clock Multiplier
TDP (Thermal Design Power)
Thermal Specification
Number of CPU Cores
L2 Cache
Max Processor Input Voltage (VID)
Manufacturing Process
Total Die Size
Instruction Set Extensions

Extended HALT State (C1E) Enabled
Execute Disable Bit (XD) Enabled
Enhanced Intel SpeedStep Technology
Intel Virtualization Technology (VT)
Demand Based Switching
Turbo Boost Technology
Hyper-Threading Technology
Trusted Execution Technology (TXT)
SLGT6 (R0)
2.66 GHz
1333 MT/s
4MB (2 x 2MB)
2 x 107mm²
Flip Chip LGA775

45nm Yorkfield Quad-Core

There isn't a shortage of options for those on the market for a 45nm Intel quad-core CPU. From the 3.2GHz Extreme Edition QX9770 to the 2.33GHz Q8200, Intel has the entire price spectrum covered. Those looking for a low power option can also choose from the S-series processors, which sport lower 65W TDPs. Where exactly does the Q8400 fit in to the mix?

The Q8400 operates at 2.66GHz with a 333MHz front side bus speed. It is manufactured using Intel's 45nm process technology and has a 95W thermal design power (TDP). The CPU can operate using core ratios from 6 to 8 and has 4MB of L2 cache.

Intel Core 2 Quad Q8400 Top & Bottom

Intel's Q8400 fills the $180 price point in Intel's line up that competes directly with AMD's Phenom II X4 940 BE processor. But the Q8400 has a tough fight on its hands as the X4 940 BE runs at 3GHz and offers an unlocked multiplier.

Intel Core 2 Quad Q8400 CPU-Z Details

CPU-Z reveals the processor's details and settings. Note the 4MB (2MB x 2) L2 cache shown above. This is the only difference between this processor and the more expensive 2.66GHz Q9400, which has 6MB of L2 cache. We will show you the performance difference between the two chips later on in this review.

Overclocking The Intel Core 2 Quad Q8400
Pedal To The Metal

Intel Core 2 Quad Q8400 Overclocked to 3.92GHz

We love free upgrades. One of the best ways to get more performance from your PC is to overclock the processor. From a stock frequency of 2.66GHz, we overclocked the Q8400 to an impressive 3.92GHz using a TRUE 120 and 1.36V. We started with a 333MHz FSB and raised it slowly while testing for stability along the way. It wasn't until we passed 490MHz FSB that we ran into any issues so we backed it back down and settled for the 3.92GHz overclock. We would like to note that we stayed within Intel's recommended operating voltage (0.85V - 1.3625V) to achieve this overclock. With higher voltages and more powerful cooling, even higher frequencies are likely possible.