Guide: Overclocking AMD And Intel CPUs On A Budget

Phenom II X2 550 O/C Performance And Efficiency

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AMD Phenom II X2 Test Settings
 Default SettingsOverclock Settings
CPUAMD Phenom II X2 550 3.1 GHz 1MB L2+6MB L3 Cache, 1.288V3.94 GHz (19.5x 202 MHz), 1.50V
RAMDDR3-1333 CAS 9-9-9-24, 1.50VDDR3-1616 CAS 6-6-5-18, 1.65V
MotherboardMSI 790FX-GD70 Socket AM3, 790FX/SB750, BIOS 1.3 (04/27/2009)
GraphicsZotac GeForce GTX260² 576MHz GPU, 999 MHz Shader, 896MB GDDR3-2484
Hard DriveWestern Digital VelociRaptor WD30000HLFS 300 MB, 10,000 RPM, 16 MB Cache
SoundIntegrated HD Audio
NetworkingIntegrated Gigabit LAN
Software
Operating SystemMicrosoft Windows Vista Ultimate x64 SP1
GraphicsGeForce 182.08 Desktop

A clock speed increase of 27% won’t surprise many experienced overclockers, but the Phenom II X2 550 started out at a fairly high 3.10 GHz. Its final clock rate of 3.94 GHz is fairly impressive for an AMD processor, even though the percent-gained is not. Does this increase translate directly into CPU performance?

CPU Arithmetic performance improved by 25%, while Multimedia extensions performance increased by 26%. The small difference between frequency improvement and performance improvement can likely be attributed to our use of a near-stock HT clock, as described on this guide’s previous page.

Our efforts to reduce memory timings using the processor’s highest memory ratio resulted in a tiny 8% gain in memory performance.

Average power consumption increased by 33%, mostly because of the increased CPU core voltage.

An average CPU performance increase of 26% at an average power increase of 33% yields an average efficiency decrease of around 5%. Overclockers looking for improved efficiency can instead choose a lower core voltage, as overclocking at stock voltage, though limited in performance gain, usually increases efficiency.

Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.