NZXT Precise 850w Power Supply
Author: Shawn Knight
Editor: Frank Stroupe
Date: 03-22-2007
Provided by: NZXT
Discuss: View Comments
First Look

The power supply itself is wrapped in thick bubble wrap to protect it (and its mirror finish) during shipping. A plain white box is also included inside the retail package. Opening this box we find everything needed to get up and running with the 850. This includes a user's manual, zip ties, Velcro straps, five screws, four SATA to 4-pin Molex adapters, power cable and a bundle of modular cables.

Here we see the 850 Precise from several different angles. The first thing that stands out about this unit is the mirror-like finish. NZXT calls this color "gun metal", which I do like but something more along the lines of black chrome seems more fitting. If aesthetics are even remotely important in your next power supply purchase, rest assured that this unit will look great in any system. A free-flowing honeycomb-style grill allows for maximum airflow from the 120mm cooling fan.

A power switch is located on the rear of the unit, as well as a switch for the +12v rail which can be set to "split" or "combined". This is the first power supply I have seen that offers such a switch. There has been a lot of talk the past few years with the introduction of multiple 12v rails, and even more as of late with the jump back to single 12v rails. From the outside, each method seems to have its pros and cons, so I decided to settle it once and for all and see which method truly is the best choice. After a bit of research, I ended up at PC Power & Cooling's website. The team at PC Power & Cooling are often considered the leading experts when it comes to power supplies. I found the answer I was looking for there, and below is a direct quote from their website:

"With all the hype about multiple 12-volt rails (ads claim that two rails is better than one, five is better than four, etc.), you'd think it was a better design. Unfortunately, it's not!

Here are the facts: A large, single 12-volt rail (without a 240VA limit) can transfer 100% of the 12-volt output from the PSU to the computer, while a multi-rail 12-volt design has distribution losses of up to 30% of the power supply's rating. Those losses occur because power literally gets “trapped” on under-utilized rails. For example, if the 12-volt rail that powers the CPU is rated for 17 amps and the CPU only uses 7A, the remaining 10A is unusable, since it is isolated from the rest of the system.

Since the maximum current from any one 12-volt rail of a multiple-rail PSU is limited to 20 amps (240VA / 12 volts = 20 amps), PCs with high-performance components that draw over 20 amps from the same rail are subject to over-current shutdowns. With power requirements for multiple processors and graphics cards continuing to grow, the multiple-rail design, with its 240VA limit per rail, is basically obsolete.

So there we have it, as the guys on the Discovery channel would say, myth busted! With that said, I will be leaving this setting on "combined" during testing. Anyway, we find a specs sticker on the side of the 850 detailing its power output. The "front" of the unit has the main cables hard-wired in and provides a modular system for all other cables. As mentioned earlier, modular power supplies are great for keeping your system clean and cool. But do remember that there is a slight risk involved. Adding an extra "link" in the system increases the electrical resistance and could lead to a slight loss of power vs. a hard-wired system. But, in all of my experience, I have never had a problem with modular systems and will continue to use and recommend them.

More of the 850 and its cables just ahead...

  Sponsors Links

  Sponsors Links