WattSmart 750W Power Supply

Posted on March 27, 2008
Author: Sean Potter
Pages: 1 2 3 4 5 6

Usage & Performance

While the power requirements for components such as video cards continue to skyrocket, most other components' power requirements as decreasing. Between SATA hard drives and DDR2 RAM, I'm beginning to think I wouldn't be able to draw a full 750 watts of power from this power supply.

Just to be sure I got a good draw on the machine, I moved my 8800GTX video card, two additional hard drives, three Vantec Tornado case fans, and about eight cold cathodes to the vicinity of this case and hooked them all up. This brought the grand total of hardware to a Core2 Duo E6300, 2GB of Crucial Ballistix Tracer DDR2 RAM, a GeForce 8800GTX, five SATA2 hard drives, six cold cathodes, and 7 case fans.

I made sure none of the fans in the case were thermally controlled, then started a game of Unreal Tournament 3 on high settings to get the full usage out of both the video card, RAM, and processor. Below, you can find my results from testing:

Input Output
+12v (Rail 1) 20 A (240W)
+12v (Rail 2) 14 A (168W)
+12v (Rail 3) 10 A (120W)
+12v (Rail 4) 12 A (151W)
-12v .5 A (6W)
+3.3V 3 A (20W)
+5 VSB 3 A (15W)
DC Power: 720W
AC Power: 900W
Efficiency (DC/AC): 80%

To measure AC wattage, I used a Kill-a-Watt, purchasable from ThinkGeek. These devices are relatively inexpensive, but a giant help in measuring your equipment's power usage. To measure the wattage, amp, and current on the separate rails, I used a voltammeter. I have a rather simple voltammeter that I can only check on the current and voltage. This isn't a problem, because the wattage of a line can be found in the simple equation, Amps * Volts = Watts.

Dual-ball bearing fans are designed for longer lives and energy efficiency. The two 80mm fans on the EPSPOW750PRO no doubt add to the unit's power efficiency, but they are not the quietest of fans. For desktop use, the noise may go unnoticed, but this isn't a power supply meant for home theater machines. Thankfully, even as the power usage increases, the fans do not seem to get any louder.

Unreal Tournament 3 doesn't draw a full 99-to-100% pull on the CPU usage, so I decided to take things one step further and benchmark the system using OCCT.

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