Our testing methods
As ever, we did our best to deliver clean benchmark numbers. Tests were run at least twice, and the results were averaged.

Our test systems were configured like so:

ProcessorOpteron 148
Opteron 152
Opteron 175
Dual Opteron 248
Dual Opteron 252
Dual Opteron 275		Xeon 3.2GHz (Nocona 1MB)
Xeon 3.4GHz (Nocona 1MB)
Dual Xeon 3.2GHz (Nocona 1MB)
Dual Xeon 3.4GHz (Nocona 1MB)		 Pentium 4 660 3.6GHz
Pentium D 840 3.2GHz
Pentium Extreme Edition 840 3.2GHz
System bus1GHz HyperTransport800MHz (200MHz quad-pumped)800MHz (200MHz quad-pumped)
MotherboardTyan Thunder K8WE S2895SuperMicro X6DAL-GIntel D955XBK
BIOS revision2/21/2005 beta080010BK95510J.86A.1152
North bridgenForce Professional 2200
nForce Professional 2050
AMD 8131 PCI-X Tunnel		Intel E7525955X MCH
South bridge6300ESBICH7R
Chipset driversSMBus driver 4.45
IDE driver 4.75		OS integratedINF Update 7.0.0.1019
Memory size2GB (4 DIMMs)2GB (4 DIMMs)1GB (2 DIMMs)
Memory typeOCZ PC3200 512MB registered ECC DDR SDRAM at 400MHzKingston PC3200 512MB registered ECC DDR DRAM at 333MHzCorsiar XMS2 5400UL DDR2 SDRAM at 533MHz
CAS latency (CL)32.53
RAS to CAS delay (tRCD)332
RAS precharge (tRP)332
Cycle time (tRAS)878
Hard driveMaxtor DiamondMax 10 250GB SATA 150
AudioIntegrated nForce/AD1981B
with NVIDIA 4.60 drivers		Integrated 6300ESB/ALC650
with Realtek 5.10.0.5820 drivers		Integrated ICH7R/STAC9221D5
with SigmaTel 5.10.4456.0 drivers
Graphics GeForce 6800 Ultra 256MB PCI-E
with ForceWare 71.84 drivers		 GeForce 6800 Ultra 256MB PCI-E
with ForceWare 71.84 drivers		 GeForce 6800 Ultra 256MB PCI-E
with ForceWare 71.84 drivers
OSWindows XP Professional x64 EditionWindows XP Professional x64 EditionWindows XP Professional x64 Edition
OS updates---

Note that we have less total memory on the Pentium setups. I don't believe any of our benchmarks are constrained by available RAM in a 1GB system, but you'll still want to keep the difference in mind.

All tests on the Pentium systems were run with Hyper-Threading enabled, except where otherwise noted.

Thanks to Corsair, OCZ, and Kingston for providing us with memory for our testing. This matchup required lots of high-quality RAM, so we had to spread the love around. All three brands are far and away superior to generic, no-name memory.

Also, all of our test systems were powered by OCZ PowerStream power supply units. The PowerStream was one of our Editor's Choice winners in our latest PSU round-up.

The test systems' Windows desktops were set at 1152x864 in 32-bit color at an 85Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

We used the following versions of our test applications:

The tests and methods we employ are generally publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.