Power Supply Unit (PSU)

Efficiency:

• Ratio of the provided output electric power versus the used input electric power. Ideally, it should be 1 (100%) but in reality it is always less, as an efficiency of 100% that would mean zero losses

Other builders use 500W or 520W PSU. How can the Corsair, only 430W, be better?

• Power supplies are probably the components most subject to inflated ratings, and the generic units cannot deliver the claimed wattage. In addition to the optimistic claims, the generic units usually list the capacity as "max capacity", meaning that wattage (if it was there in the first place) would be delivered for only a short amount of time; they list the continuous (again, even if that one was true) in much smaller font. Furthermore, delivering the rated capacity is only part of the story. The voltage has to be stable, clean, low ripple, low noise (harmonics) and the power supply has to cope well with unexpected loads... oh, and before I forget, efficiency also.

The reputable brands rate their power supplies at the real capacity. The not so reputable brands will stretch the numbers, and the downright shody brands will straight out lie. Furthermore, while a power supply can provide 3 different voltages (3.3 V, 5V and 12V) the 3.3V and 5V lines that were used heavily in PCs with older CPUs (Athlon K7, Pentium III and older) are not in newer ones. A modern computer takes most of its power from the 12V line (12V rail) The good brands provide most of its rated capacity in the 12 V rail, while the not so reputable brands will provide most of its power on the 3.3V and 5V lines, knowing well that it will never be used, and hence, they can still playing the numbers game to claim a total wattage, even if more than half of that wattage is unusable.

As example: Let's take the Corsair CX430 v2.3, it provides 32A in a single 12V rail, meaning that 384W of the total 430W are available there for CPU, video cards and storage. Now let's take the electronics store house brand "520W" PSU. For starters, the generic one states clearly that 520W is peak, meaning transient only, continuous is only "420W", already lower than the CX430. Let's keep digging, the label doesn't even mention 12V ratings, but after some google searching you find it has 2 12V rails, one rated at "18A" and the other at "16A". If those were true, you have 34A in the 12V rails, or 408W truly available. But wait, more google searching reveals that the combined 12V load between those 2 rails cannot exceed 20A, meaning only 240W are truly usable. Big difference, right? Less than half of the "520W" are usable. To make it worse, the "520W" unit has lower efficiency, poor voltage regulation, NO short circuit protection and no active PFC. "but, but, it was 520W, it has to be better..."

Wait, if you didn't have enough, that "520W" unit is not the worst of the generic units. The "500W" or "480W" that are bundled with the cases are even worse! The "500W" is rated at only "16A" in a single 12V rail, and by my quotation marks, you know that I doubt it can give those 16A without burning down in flames... Do you want your precious components to serve as test bed if it can hold up or not? You get what you pay for, price wise, you can walk into any computer store and get a "500W" PSU for less than $20, the CX430 is more than double that price, so do you really expect the cheapie to be better? Indeed, you get what you pay for. Of all the components in the build, PSU is not the one to go cheap. Furthermore, if still worried about the number on the label, we offer upgrades to REAL 500W and 600W PSUs, and while the upgrades are better financially for us, in truth, they are not needed for several configurations. We would love to have everyone upgrade their PSUs, more money for us! But, not really needed for several configurations. could keep explaining more about power supplies, but for the curious minds I will recommend to do some reading at what is probably the best website for power supplies reviews on the whole Web: Gabriel Torres' Hardware Secrets

The Radeon HD 7770 box says "500W" PSU required, the box of the HD 7850 says "550W required". Would the Corsair 430W be enough?

• Video card manufacturers are well aware that many users will try to power that shiny new video card with a generic power supply, so to minimize the risk to the video card, they inflate the numbers and require "500W" knowing that when generic "500W" PSUs are used, the 300W only or so needed in reality can be met. Using a PSU calculator reveals that a Radeon HD7770 doesn't use more than 100W during gaming a HD7850 no more than 140W, and the reviews on the web match those numbers. Check my PSU calculator screenshots to see what the system really consumes. These are very power efficient video cards, but obviously, the makers want to minimize returns caused by those generic power supplies

Ripple:

• As the output DC voltage is generated from converted AC, even after filtering, the output signal is not a flat line, but rather a series of spikes up and down around a given voltage level, resembling a group of mountains. The lower the ripple, the better.