Testing:

The Seasonic S12D 750W power supply was installed in a test system with the following components:

»Intel Core i7 920 (2.66GHz)
»Prolimatech Megahalems Cooler
»eVGA x58 SLI Micro Motherboard
»2xBFG GeForce GTX 260 MAX CORE 55 896MB PCIe Video Cards in SLI
»Western Digital Caviar Black 1TB SATA 3Gbps Hard Drive
»OCZ Platinum PC12600 1600MHz DDR3 Triple-Channel memory
»Windows 7 Ultimate x64



In order to test the Seasonic S12D, we used a Kill A Watt 4400 and an Ideal 61-310 Multimeter. Each test run started with a 30 minute period where only Hardware Monitor was running, after which idle readings were taken. For load readings, we ran a combination of Prime 95 (with all 8 instances), SiSoft Sandra Professional’s Burn-In Test, and FutureMark 3DMark Vantage.

For comparison purposes, we ran the Seasonic S12D against two other popular 750W power supplies:

» Cooler Master Real Power Pro 750watt (RS-750-ACAA-A1)
» PC Power & Cooling Silencer 750 EPS 12v Quad/Black

In the first chart takes multimeter data to compare the three main rails at both idle and under load for just the Seasonic S12D 750. There was almost no voltage fluctuation even when we got around the 470 Watt range. While this is no where near what this unit can do, it barely flinched.



In the second graph, multimeter data is compared for all three power supplies under load conditions. Overall we see that the S12D's voltages run a bit higher than the other two tests subjects, but that all units are within specification. The 3.3V rail at 3.43V does seem a bit high, but it's only a 0.4% fluctuation so no worries. The same holds true for the 5V rail, while the 12V rail only fluctuates 0.2%.