We summarized below all CPUs included in this review with their main specs.

CPU	Cores	Internal Clock	External Clock	L2 Memory Cache	Platform	TDP
Core 2 Extreme QX6700	4	2.66 GHz	1,066 MHz (266 MHz x 4)	4 MB x 2	Socket 775	130 W
Core 2 Extreme X6800	2	2.93 GHz	1,066 MHz (266 MHz x 4)	4 MB	Socket 775	75 W
Core 2 Duo E6700	2	2.66 GHz	1,066 MHz (266 MHz x 4)	4 MB	Socket 775	65 W
Pentium 4 550	1	3.4 GHz	800 MHz (200 MHz x 4)	1 MB	Socket 775	115 W
Pentium 4 640	1	3.2 GHz	800 MHz (200 MHz x 4)	1 MB	Socket 775	84 W
Athlon 64 X2 5000+	2	2.6 GHz	*	512 KB x 2	Socket AM2	89 W

* Since AMD64 CPUs have their memory controller embedded in the CPU, the datapath between the CPU and the memory controller uses the CPU internal clock rate instead of an external clock rate as it happens on Intel CPUs. To communicate with components outside the CPU, AMD64 CPUs have two busses, the memory bus and the HyperTransport bus. The memory bus run up to DDR400 or DDR2-800 depending on the platform (socket 939 or socket AM2, respectively) and the HyperTransport bus of the listed CPUs works at 1,000 MHz transferring two 16-bit data per clock cycle (also labeled as “2,000 MHz”), achieving a 4,000 MB/s transfer rate on each direction. A 800 MHz external bus on Intel CPUs can provide a maximum theoretical transfer rate of 6,400 MB/s while a 1,066 MHz external bus can provide up to 8,528 MB/s. Direct comparison of this particular spec between Intel and AMD CPUs is really tricky as Intel external bus is used for both accessing the main RAM memory and other components – the video card in particular –, while on AMD64 CPUs two separated paths are used. Also, on Intel CPUs the same datapath is used for transferring data in and out, while HyperTransport bus provides two separated paths for input and output.

Unfortunately Intel didn’t provide us a Pentium D or a Pentium Extreme Edition samples for reviewing. Also we had to send the Athlon 64 FX-62 we had back to AMD (they only lend us the CPUs, we have to send them back after publishing the review). We asked AMD to send us Athlon FX-62 again for this new review and we got no answer from them. A pity.

By the way, the present review is far more accurate than our previous review on Core 2 Extreme X6800 and Core 2 Duo E6700 CPUs. You may find several discrepancies between the two. In such cases, please consider the results from the present review and discard the results we published before.

We changed all our methodology entirely in order to present values closer to reality. We have changed five points: the amount of memory (2 GB against 1 GB), the video card (GeForce 7950 GX2 against GeForce 7800 GTX), the hard disk drive (80 GB SATA-300 against 40 GB ATA-133), the power supply (Antec Neo HE 550 against OCZ ModStream 520 W) and the programs we used (we included far more programs now).

We would like to thank all our readers (and also Intel) that pointed out that something was wrong with our previous review, with numbers lower than other websites were getting. Even though the numbers were correct for the hardware parts we used, we surely had to use more high-end parts for making the review closer to reality. It is obvious that no one buying a high-end Core 2 will use a 40 GB ATA-133 HDD, for example.