Overclocking Results:

stock max. oc processor speed: 3.2mhz 4.02mhz if you're new to Overclocking and not sure what to do, check out these two excellent Guides for some pointers: Overclocking the CPU and Memory Overclocking the Videocard

The Intel Pentium D 840 is comprised of two 90nm Prescott cores bumped together, which is logical enough in terms of basic function, but has some interesting ramifications for overclocking. Since both cores share the same die, FSB and heatsink, will they end up stepping on each other's toes during overclocking and reduce overall headroom compared to a single core processor?

With an eye to finding out, we used a Gigabyte GA-81955X Royal test platform to overclock the processor as high as it would go on air cooling...

Starting with the memory running at 533MHz, we began increasing the FSB in 5-10MHz increments. We ran into trouble immediately, with the system refusing to boot at 210MHz. Increasing chipset voltage by 0.1V and memory voltage by 0.2V fixed this. The next snag hit at 230MHz FSB. The only way we could get the motherboard to boot was by reducing its internal memory speed to 400MHz and increasing chipset voltage by 0.3V. The processor also needed some more voltage, to the tune of 1.35V.

Moving up through 235MHz, 240MHz and 245MHz, we increased chipset voltage to the +0.35V maximum, and ended up running the CPU at a toasty 1.45V. Our final destination turned out to be 251MHz; anything beyond this would result in failed benchmarks and random crashing. CPU temperatures peaked at about 56C, warm but not critically so.

251MHz FSB translates to an overall speed of 4.02GHz for the Pentium D 840 test processor. This is a fairly hefty 820MHz overclock and we were well satisfied, especially considering the 955X Express chipset we used is brand new and untried. It seems like doubling the cores is not going to hold back the overclocking performance of the Pentium D to any great extent. Up next, the benchmarks you've been looking forward to!

Test System Specs

We decided to test the Intel Pentium D 840 against its closest obvious competitor, AMD's dual-core Athlon64 X2 4800+, as well as a selection of the most recent single-core processors from both Intel and AMD. This should give us a good idea of where the new dual-core chips stand in terms of performance.

We also loaded WindowsXP x64 Edition onto the two dual-core processors and ran a second suite of benchmarks to compare performance on the 64-bit operating system(s) of the future.

PCStats Test System Specs:

system 1 system 2 processor: intel pentium 4 540 intel pentium d 840 athlon64 4000+ athlon64 x2 4800+ clock speed: 16 x 200 MHz = 3.2 GHz 16 x 251 MHz = 4.02GHz 12 x 200 MHz = 2.4 GHz Motherboards: Gigabyte GA-8ANXP-D, i925X Gigabyte GA-81955X Royal, i955X DFI LANParty NF4 SLI-DR Videocard: MSI RX800XT-VTD MSI RX800XT-VTD Memory: 2x 512MB Crucial Ballistix PC2-5300 2x 512MB Corsair TwinX3200XL PRO Hard Drive: 74GB Western Digital Raptor 74GB Western Digital Raptor CDROM: MSI X48 CD-RW/DVD-ROM NEC 52x CD-ROM PowerSupply: Vantec Stealth 470W Vantec Stealth 470W Heatsink: Thermaltake Jungle 512 Prometeia Mach II GT (review) Software Setup WindowsXP Professional WindowsXP x64 Edition Intel INF 7.2.1.1003 Catalyst 5.6 WindowsXP Professional WindowsXP x64 Edition nVIDIA nForce4 6.53 Catalyst 5.6 Benchmarks SYSmark 2004 Business Winstone 2004 Content Creation 2004 SiSoft Sandra 2005 Cinebench 2003 (32/64 Bit) Maya Render Test ScienceMark 2.0 (32/64 Bit) Super Pi 1.1 Hexus piFast 4.1 POVray 3.1g PCMark04 PCMark05 3DMark2001 3DMark05 Comanche 4 UT2003 UT2004 Doom 3