The Intel Pentium D 840 performed well in the office and rendering benchmarks, but comparatively less so on the pure number crunching and gaming tests. Any benchmark that involved multi-threading or multitasking allowed the processor to flex its muscles, increasing scores considerably over its single-core equivalent.

We were pleasantly surprised to get an 820MHz overclock out of the Intel Pentium D 840 on air cooling. Given that the processor is using a brand-new chipset for testing, this is not bad at all.

In some respects, pitting the Intel Pentium D 840 against the AMD Athlon64 X2 4800+ is not a fair match up. While both processors are at the top of their respective lines, the Athlon64 X2 4800+ costs almost double the price of the Intel CPU. It's not surprising that the AMD dual-core chip is faster at gaming and mathematical operations either, since single-core Athlon64 processors enjoy the same advantages over Intel Pentium 4 chips.

It comes down to economics in the end. For a business that needs multi-tasking, multi-threading capabilities, the Pentium D 840 may be the better buy where sheer cost is the primary concern. For an application that needs maximum single and dual-core performance regardless of costs, the AMD Athlon64 X2 4800+ comes out on top. For the home user that just wants to play games fast, neither processor is ideal, one being too pricey, the other slower than comparably priced single-core chips.

One interesting fact we noted with both Intel and AMD dual-core processors is that the amount of reported memory bandwidth was lower than their single-core equivalents. We'd hypothesize that this is because of the inherent overhead of communication between the two cores on the die. The Intel Pentium D 840 also needs to use the FSB to transfer data between cores, so this would be an obvious possible area of slowdown. Of course, it could also be that the 955X Express platform we tested the Pentium D 840 on is still immature. The effect of internal memory speed on Pentium D performance is quite noticeable, as we mentioned earlier in the review.

The Intel Pentium D 840 has taught us one now-indisputable fact about the nature of dual-core CPUs: Just because it has two cores doesn't mean it's going to be faster at everything... But now we're being unreasonable.

The Intel Pentium D 840 behaved exactly as you would expect a processor made of two standard 3.2GHz Prescott Pentium 4 cores to do. It excelled on any and all benchmarks which involved multi-tasking or multi-threading, and otherwise performed exactly like a single-core Intel Pentium 4 3.2GHz processor.

Given that Intel has not priced the Pentium D line of processors above faster single core chips, loyal Intel users are faced with a fairly simple choice: If the things that you do with your computer everyday involve multi-tasking or multi-threaded applications, a dual-core Pentium D processor will give you the most bang for your buck. If you primarily play games, do not engage in heavy multi-tasking or do not use multi-threaded applications, a single-core Pentium 4 processor clocked faster than 3.2GHz will give you better performance every time.

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