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Perhaps the most obvious aspect of the Cooler Master 850W PSU is the size of its box. No, seriously! Power supplies usually come in boxes barely big enough to hold them. Their wires are all bundled and knotted together, a user manual is tossed in there somewhere, and four screws to attach it to your case if your lucky. But the Cooler Master RS-850-EMBA comes in what can only be termed as a very pretty cardboard crate. But enough about the box, let's look at what came with our supply.

Of course, we get the Cooler Master Real Power 850W supply. And we get a detailed user manual written in eight different languages. Cooler Master tossed in four case screws to help attach our supply to a box. That little desiccant pack keeps everything nice and dry. In fact, it might be a good idea to start tossing those inside a computer case. You know, just to help sponge up any unwanted moisture that could threaten expensive parts. And we get a power cord. But this isn't just any power cord.

In talking with Cooler Master, we were told why they chose to use such a beefy cord. They told us it was because of the added power that the RS-850-EMBA draws. Granted, it can only draw a maximum of 15 amps current. It can only do this because of how house hold circuits are commonly limited to 15 amps. Most people don't have much use for anything over 15 amps, unless your like me, with a small shop full of industrial tools that you'll probably won't find at any home improvement store. But back to the cord. Typically, most PSU chords are of a 18 AWG wire. AWG stands for American Wire Gauge, and it's how wire is measured. The higher the number, the finer the conductor within the cable. The lower the number, the thicker the conductor within the cable. Just take a look at the following pictures as an example.

As you can see, our Cooler Master came with a thick 14 AWG cable. This heftier copper core, which costs 3 times as much as 18AWG cable, means it is far easier for electrons to pass through. Had it been anything above say a 20 AWG, then there would be quite a bit of resistance generated and some considerable amount of heat as a by product. That would mean inefficient use of power, some power loss, and a potential fire hazard. I know, its kinda funny how a higher AWG number means a finer wire, it seems back wards. But in this case, driving an 850W power supply with the biggest cord possible is the right thing to do.

Next up is the warning sticker. I found this very bright little tag over top the power receptacle on our Cooler Master supply. And this stickers right, it can be dangerous to run this power supply beneath its rated power demands. If we were to plug the Cooler Master 850W supply into a wall socket that was rated for 115V at 10A, we could see some problems. The voltage requirements won't make much of a difference if they're off by only a few volts here and there. But the required amperage could cause a power supply to over heat. This supply wants 15 Amps in so it can step up that power to those voltage rails. If it's fed far less than 15 Amps, then it will have to work extra hard to step up or step down that current. This extra work can create loads of heat, and extra heat can shorten the life of a power supply, and perhaps even kill it.

And perhaps just as important is not plugging this supply into a power bar. Now I know we're all guilty of this, but with high wattage power supplies, sharing a single circuit with other appliances can spell trouble. Having your high wattage PSU, a big CRT monitor, coffee machine, mini-fridge, printer, desk lamp and speakers all riding on the same circuit is a bad idea. That will place an unnecessary amount of load upon that circuit and cause the circuit breaker to trip. So it's best to have these high wattage PSUs on a circuit of their own, just for efficiencies sake.

On to the supply itself. And my first big question is . . .  Where's my Power Switch? Again, we had to talk with Cooler Master for this one.  According to Cooler Master's product manager, the lack of the switch was a design decision to avoid damage by an "onrush" of power.  The input current of the PSU is a max of 15amps from 90V AC input on a 100% load, and Cooler Master decided to ensure that every time the power is turned on the PC that the PSU will start with a "warm start".

Despite the missing power switch, there is a single dual colour LED on the rear of the PSU. It glows green when active, and glows red when off. Neat, but not nearlly as useful as a power switch may have been.

The one major draw back with this absence of a switch is how to turn the PSU off safely. There have been occasions where I've screwed up Windows so badly (on purpose mind you) that my only salvation is the power switch on the power supply. Now you could yank the power cord from the supply or wall, but that can create other problems. Occasionally, it can cause power spikes or drops that can damage hardware, and can sometimes even corrupt data if the hard drive is still actively spinning. I don't like this missing switch. My solution is a pretty simple one. I would go to the local home improvement store and buy a wall switch rated to carry 15 Amps. They're out there along with number 14 AWG wire, electrical boxes and a few other parts I'll need. I'd hack together some of the 14 AWG wire with that 15 Amp switch and receptacle. An electrical box and plug to finish things off and I've just built a power switch box for the Real Power Pro 850W. Now the parts in these loosely laid plans may seem simple, but playing around with electrical wiring is something only a qualified individual should do. So be fore warned, there is the potential to cause some damage by doing this, so do your homework and before you decide to start playing around with electricity.  

Next on our list is the physical size of the Real Power 850W Pro. As you an see, it's quite a bit bigger than your average ATX supply. Here it is pictured next to one of our recently reviewed ThermalTake 750W Tough Power Cable Management PSU. That was a nice supply with modular cables and standard physical dimensions. The Cooler Master 850W Real Power Pro on the other hand, it's a fair bit longer than its cousins.

As the figures show, the Cooler Master 850W is 20 millimetres, or about an inch longer than other standard ATX power supplies. And though the mounting points are identical (it is a standard) I might find some difficulty trying to stuff this behemoth into a mid-tower ATX case. Its extra size might complicate cable management and air flow issues.

As we start to look inside the 850W Real Power, there are a number of engineering advancements that I quite like. And perhaps the first one I'll touch on are the two blue thermal probes. These thermal probes are supposed to be held down by some plastic heat shrink tubing, a type of soft plastic tube that you can buy at local electronics stores. It's used to seal connections. If one were to be splicing some wires together, they could use heat shrink rather than plain old electrical tape. In this case, the heat shrink tubing was used to securely adhere these two thermal probes to a couple of fins on the heat sinks. Presumably there is a thermal switch buried somewhere in the inner reaches of this power supply. If the supply should start to overheat due to system load, then the thermal switch would pick up the extra heat in the heat sink fins and turn the fan up to high speed. A great option, considering that there are those moments of surfing the web and typing up documents that draws hardly any current from a PSU. Why have a noisy fan running at full tilt all the time?

What else hides inside? Well, I like the dual transformers. They help to step up and step down the current needed to help power your computer and all of its components. Typically, ATX power supplies will have only one transformer. Well, not completely true. There is the primary transformer and then a smaller secondary transformer. But in the case of the Cooler Master 850W, we have two primary transformers and a single smaller secondary transformer. You can identify them in the following picture as they all ave a yellow banding on top of them. As for whether this extra transformer makes any real difference, yes it does. It makes it easier for the supply to crank the voltages and amperages up and or down. Typically, ATX power supplies use a single primary transformer to change the voltage and amperage, and switch its inputs to get different outputs. It's kinda difficult to explain fully, but having that extra transformer in the Cooler Master 850W is somewhat like having a dual core processor. The work is distributed, and is there for more efficient.

I was quite impressed with the quality of heat sinks that Cooler Master used in this supply. Upon inspection, they appear to be pieces of Aluminium T-channel that has been cut to act as heat sinks for the SCRs (Silicon Control Rectifiers). These SCRs can get quite hot, and will burn out if not sufficiently cooled. Good cooling is a must in any power supply. The large 135mm fan helps too.

One other thing I had noticed inside the Cooler Master 850W was this plastic shield. Though not completely necessary perhaps, it does help to prevent the possibility of any components within the supply from touching the metal casing. It wouldn't take much to short out the components inside a power supply, and this plastic shield helps to prevent any accidental sparks from flying. In fact, I accidentally shorted out an open PSU once. The sparks were pretty, but the dead supply was sad.

Most everything else on the Cooler Master 850W is standard. The power connectors are standard, and everyone uses this type of wire loom to help tame the power cables. Though I will say, the Black Chrome finish on the Cooler Master 850W is exquisite.