FAQ: Corsair HX series features and functionality!

[Power Guy]

Q: I just changed my PSU from another Brand and used the cables from my old PSU when I installed my new Corsair HX series PSU and now my system will not turn on. What do I need to know?
A: You have to use the cables that come's with your specific PSU and especially cables from another make of PSU will not be compatible, even cables from a HX520/620 would not be compatible with an HX1000 PSU for example.
Please use only the cables that comes with your new PSU other wise you may damage your system components.

Q: I know almost nothing about power supplies. What do I need to know?

A: A power supply converts AC power from your wall socket into usable DC power for your computer. Different types of computers require different amounts of power. In fact, even a minor change such as adding a hard drive or a new graphics card can change the power requirements of a machine drastically. So how do you pick a quality power supply that will provide clean and ample power to your expensive components? The first step is educating your self, so let’s talk about some of the critical power supply specifications, like voltages and currents, power factor correction, efficiency, and stuff like that...

Q: What are voltage are provided by the power supply and how are they used?

A: Power supplies for personal computers generally provide three voltages; 3.3 Volts, 5.0 Volts, and 12.0 Volts. There are other voltages, such as -12V and +5Vsb, but for right now, let’s focus on the “big three”. On modern systems, the +12V rail(s) is used more than the +5V or +3.3V. The +12V is responsible for powering your CPU, your video cards, and other power-hungry critical system components. The 3.3V and 5V rails generally provide power to sections of the system where not as much current is required.

Q: What does “efficiency” mean?

A: Simply put, it’s an easy way to gauge how much of the power that your power supply is drawing from the outlet is being provided to the computer and how much is being converted to heat. For example, if a power supply is 60% efficient, and it produces 600W of power, it could draw up to 1KW from the wall socket! The other 400W would be converted to heat. Corsair’s HX series is 80%+ efficient, currently among the industry’s best for PC power supplies. A high efficiency rating also means that your power supply will draw less power from the wall at similar outputs, saving you money on the power bill.

Q: What is Active Power Factor Correction, and why do I need it?

A: Essentially, power factor is a measurement of how effectively electrical power is being used. There are two major types of PFC, Active and Passive. Active PFC provides better performance, with a PFC rating of nearly 100%, and is used on all Corsair HX series power supplies.

Q: What are modular cables? Why are they good?

A: Modular cables are cables that can be disconnected from the power supply. A typical power supply has permanently attached cables that cannot be detached, even if they are not used. The HX series has modular cables that allow you to choose which cables you need and to use only those cables, allowing for less clutter and more airflow through the case.

Q: How do I know how much power I need?

A: Well, the short answer is that the Corsair HX520 is great for most system builds, and that the HX620 will supply more than enough power for the most aggressively over clocked system builds, even with multiple graphics cards.

In fact, calculating the actual power needed is fairly complicated. Type “power supply calculator” into your favorite search engine, and check out some of the results. Keep in mind that more power can not hurt you and allows for future expansion, while not enough power can cause failures and stability problems. So give yourself some breathing room!

Q: Why is there such a large range of prices on, say, 500W power supplies?

A: Some manufacturers hide their true performance numbers by rating their PSU at unrealistic temperatures. For example, many low-end power supplies are rated at 25C instead of a more realistic 45C or 50C. This means that while that 500W PSU for $40 looks good, it might only be rated at 500W at 25C, and in your computer’s case where the ambient temp can climb to 45C or higher, it will drop output, sometimes dramatically!

In addition, total wattage is calculated across all three system voltages. You want to make sure that your supply has a very high percentage of its total wattage on the 12V rail, as this voltage is used to drive the most power-hungry components.

Keep in mind that high quality components cost more, and when a manufacturer cuts corners to cut costs, what they’re really cutting is reliability, stability, and quality. You are using this power supply to drive large amounts of electrical current into expensive processors and graphics cards, not to mention into disk drives that contain important information. Make sure you have lots of confidence in your PSU selection!

Q: What about noise? How can I make sure my new power supply is going to be quiet?

A: Noise typically comes from moving parts, and the power supply only has one moving part, the fan. Naturally, cooling is all about airflow. Airflow is a simple formula of fan design, RPM, and fan size. Since most fan designs are fairly similar, we can limit ourselves to the RPM and fan size. A smaller 80mm fan will have to spin much faster to push the same air that a larger 120mm fan can produce. The higher the RPM, the louder the fan will be. The Corsair HX series power supplies use a thermally controlled 120mm fan. What this means is that when the PSU is in heavy use, for example during an intense gaming session, the fan will sense the temperature of the PSU rising, and spin up to a higher RPM to push more air. But when the PSU is not being used heavily, like while browsing the web and listening to some MP3s, the fan will sense the temperature of the PSU and decrease in speed and noise. A smart fan is a quiet fan.

Q: So which Corsair power supply should I buy, the 520W or the 620W?

A: That all depends on your needs and budget. The 520W is significantly less expensive than the 620W, but the 620W is more powerful. A major difference is the fact that while they both have similar +12V ratings at 18A each, the 620W power supply can do a combined total of 50A on the +12V rails, while the 520W can provide 40A on the +12V rails. The 520W would be more than enough for an enthusiast running dual mid-range video cards and a moderately over clocked power hungry processor with a few hard drives. The 620W would be more than enough for the absolute enthusiast who is running two high-end video cards, an extremely fast processor that is over clocked heavily, and just about anything else that could be thrown at it. It’s really up to you to decide which supply meets your needs.