Loading up The Beast
A cornerstone of our power supply testing methodology is a custom-built load generator created by forum regular justbrewit that we like to call The Beast. If you're unfamiliar with its frightening array of resistors, I strongly suggest checking out this page from our first round-up to use The Beast, which details the rig's internals and our testing methodology.


Behold The Beast!

We use The Beast to push each PSU to 25, 50, 75, and 100% of its output capacity while measuring DC voltage, AC ripple content, and gathering data that can be used to calculate overall efficiency. However, since The Beast is limited to applying loads in 2A increments, we borrow a page from The Price is Right and use amperage loads that come as close as possible to our targets without going over. The chart below shows the amperage loads applied to each PSU.

Total loads (Amps)
25% 50% 75% 100%
3.3V 5V 12V 3.3V 5V 12V 3.3V 5V 12V 3.3V 5V 12V
Antec Basiq 350W 2 2 4 6 6 8 10 10 14 12 12 18
Corsair VX450W 450W 2 2 6 6 6 14 10 10 20 12 12 28
Enermax MODU82+ 425W 2 2 6 4 4 12 8 8 20 10 10 26
FSP Blue Storm II 400W 2 2 4 6 6 10 10 10 16 14 14 22
OCZ ModXStream Pro 500W 2 2 6 6 6 14 10 10 22 14 14 30
SolyTech SL-C350ATX 350W 4 4 2 8 8 6 14 14 10 18 18 14
Tagan Silver Power SP-SS400 400W 2 2 6 6 6 12 8 8 18 12 12 24

When testing with The Beast, each power supply was hooked up using its primary and auxiliary 12V connectors, and when available, two PCIe power connectors and six 4-pin peripheral connectors. We used a Pico ADC-212 digital oscilloscope to probe the 3.3 and 5V wires on the primary power connector. 12V lines were probed in the primary power connector and also with one of the PCIe power connectors. In the graphs on the following pages, 12V power from the primary connector will be marked 12V1, while power from the PCIe connector will be 12V2. Since our Antec and SolyTech units lack PCIe power connectors, we used the 12V component of one of their 4-pin peripheral connectors as a secondary reading.

Rather than calculating efficiency based on static 3.3, 5, and 12V, er, voltages, our calculations take into account the actual DC voltage delivered on each line during testing. This should compensate for any voltage fluctuations that some PSUs exhibit under load.

Our testing methods
Testing was conducted in two parts. First, PSUs were run in the system detailed below for a series of power draw, temperature, and noise level tests. They were then hooked up to The Beast to test power delivery and overall efficiency.

All tests were run three times, and their results were averaged.

Processor Athlon 64 X2 5000+ 2.6GHz
System bus HyperTransport 16-bit/1GHz
Motherboard Asus M2N32-SLI Deluxe Wireless Edition
Bios revision 0906
North bridge nForce 590 SLI SPP
South bridge nForce 590 SLI MCP
Chipset drivers ForceWare 9.35
Memory size 1GB (2 DIMMs)
Memory type Corsair CM2X512A-5400UL DDR2 SDRAM at 742MHz
CAS latency (CL) 5
RAS to CAS delay (tRCD) 5
RAS precharge (tRP) 5
Cycle time (tRAS) 12
Audio codec Integrated nForce 590 SLI/AD1988B with 5.10.1.4530 drivers
Graphics GeForce 8800 GTS 640MB with ForceWare 162.18 drivers
Hard drives 2 x Western Digital Caviar RE2 400GB SATA
OS Windows XP Professional
OS updates Service Pack 2

We used the following versions of our test applications:

The test systems' Windows desktop was set at 1280x1024 in 32-bit color at an 85Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

All the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.