OCZ ZT Series 650W Modular Power Supply
Author: Shawn Knight
Editor: Josh Maronde
Date: 11-21-2011
Provided by: OCZ Technology
Installation / Testing

I will be using the following hardware with this power supply.

Intel Core i5-2500K Sandy Bridge
Corsair Hydro H70 Liquid CPU Cooler
Gigabyte Z68XP-UD5
MSI R6850 Cyclone PE / OC VGA
Corsair 2x 2GB XMS3 DDR3
Seagate 400GB HDD
OCZ ZS Series 750W PSU
Corsair Obsidian 650D Chassis
Optical drive
Windows 7 Home Premium 64-bit

I didn't run into any issues installing the power supply in my test system. As you can see, with a little extra effort in a case like the Corsair Obsidian 650D, cable clutter can be virtually eliminated when using a modular power supply like the ZT series. I was able to run every cable behind the motherboard tray. The only potential issue I can see is the length of the CPU cable - it was a tight fit to run behind the tray in this case but I was able to make it work.

Using a Kill-a-Watt meter, I measured the power usage of the system at the outlet, during both idle and load. To generate the load I used OCCT's power supply test utility, which stresses both the CPU and GPU up to 100%. I also ran Prime 95 for good measure. Additionally I disabled all power saving features in the BIOS. At idle, only 99 watts are being used; two less than the 750w ZS series. A full system load only generates a draw of 302 watts, or roughly 46% of what this PSU is capable of. In comparison, the 750w ZS series drew three watts less at 299 watts.

I've said it before and I'll say it again. I think a lot of people tend to overestimate just how much power a typical high-end system draws. This is a respectable system with a nice midrange graphics card that barely draws 300 watts of power under full load. As such, it really only makes sense to own a high wattage power supply if you have some serious hardware under the hood like multiple high-end video cards and / or a power sucking Socket 1366 CPU.

A quick look at the 80 Plus verification test report on this power supply shows 85.86% / 87.02% / 83.08% efficiency at 20% / 50% / 100% load with an average efficiency of 85.32%, putting it a tiny bit ahead of the ZS which scored an average efficiency of 85.18%. Our full load test of 46% puts us right near the sweet spot for this unit.

With a digital multimeter, I also took voltage readings at the back of various connectors under idle and load conditions. The +3.3V rail was the most stable, only shifting .02v going from idle to load. The +5V rail was also very stable with only a .03v fluctuation. As we typically see, the biggest fluctuation came at the PCI-e connector for the video card, which dropped .10v under full load.

Unfortunately these are the only tests we are capable of conducting at this time. We do not have access to expensive power supply testing equipment nor would we expect most of our readers to understand the detailed findings that such equipment outputs. If you are an electrical engineer or a hardcore PSU enthusiast, I would suggest you check out some other more detailed reviews on this unit or any other before making a purchasing decision.

Let's move on and wrap things up with some final thoughts and a conclusion.

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