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Intel Pentium D 840 Dual-Core LGA775 Processor Review
Intel Pentium D 840 Dual-Core LGA775 Processor Review - PCSTATS
This 90nm processor uses a pair of Prescott cores running at 3.2GHz to bring multi-processing to the desktop in a LGA775 pinless package.
 79% Rating:   
Filed under: CPU / Processors Published:  Author: 
External Mfg. Website: Intel Aug 17 2005   M. Dowler  
Home > Reviews > CPU / Processors > Intel Pentium D 840

Overclocking Intel's new dual-core processor

Overclocking Results:
stock max. oc
processor speed: 3.2mhz


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

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

Gigabyte GA-8ANXP-D, i925X
Gigabyte GA-81955X Royal, i955X


Videocard: 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
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
Catalyst 5.6

WindowsXP Professional
WindowsXP x64 Edition
nVIDIA nForce4 6.53
Catalyst 5.6


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
Comanche 4
Doom 3

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Contents of Article: Intel Pentium D 840
 Pg 1.  Intel Pentium D 840 Dual-Core LGA775 Processor Review
 Pg 2.  State of the art CPU
 Pg 3.  Intel's Dual Core Technology
 Pg 4.  Intel 955X Express Chipset
 Pg 5.  Intel 945P/G chipset
 Pg 6.  Intel E7230 Server Core Logic
 Pg 7.  Pinless LGA775 Package
 Pg 8.  — Overclocking Intel's new dual-core processor
 Pg 9.  Benchmarks: SysMark 2004
 Pg 10.  Benchmarks: Winstone 2004, Cinebench 2003
 Pg 11.  Benchmarks: Cinebench 2003 64-bit, Maya
 Pg 12.  Benchmarks: ScienceMark 2.0 in 32-bit and 64-bit
 Pg 13.  Benchmarks: SuperPI, Hexus piFast
 Pg 14.  Benchmarks: Sandra 2005, POVray
 Pg 15.  Benchmarks: PCMark04, PCMark05
 Pg 16.  Benchmarks: 3DMark2001, 3DMark05
 Pg 17.  Benchmarks: Comanche 4, UT2003
 Pg 18.  Benchmarks: UT2004, Doom3
 Pg 19.  Intel's dual-core Workhorse

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