How exactly do PSUs work?

[perfection]

My Corsair HX620W is rated at 620watts

lets say my system draws about 300watts, does that mean than my PSU draws 300W from to power socket??

Does it matter if I have a 1kW PSU, will it just draw 300W?

[K404]

Hey. In a nutshell, 240V (or 110V) comes from the mains, is rectified, transformed to 12,5,3.3V and regulated, then passed to your components.

Rectified means the AC signal is changed to a DC signal, Transformed = lower the 110/240V to what the computer uses, and regulated means the voltages stay as close to the values wanted as possible.

The voltages stay constant, but the components draw as much current as they need. Its up to a PSU to be able to supply that current.

The amount of power a PSU draws from the wall depends on the power draw of your components and the PSU efficiency.

If your components need 300W of power and the PSU is 80% efficient, it will draw around 375W from the wall.

a bigger PSU...800W, 1000W is just the ceiling of the power it can supply. you can use a 1KW PSU on a small rig, the power consumption will pretty much be the same (going back to: "the components draw as much current as they need")

:)

Thats the basics. :)

K

[Polizei]

First its transformed, then rectified I believe.

http://computer.howstuffworks.com/power-supply.htm

[perfection]

Awesome!

Of the Corsair site:

Double forward switching circuitry design offers high efficiency, up to 80% under wide load range. (http://www.corsairmemory.com/products/hx.aspx)

So does that mean my PSU is up to 80% efficient? If I got another PSU with 85% or 90% efficiency, does that mean its more energy efficient and will draw closer to as many watts as my computer needs?

[Oklahoma Wolf]

So does that mean my PSU is up to 80% efficient?

Theoretically. Double forward converting is pretty widespread these days thanks to 80+ certification, but it doesn't in itself guarantee over 80% all the time. There are other factors at work in the design of these things that impact efficiency.

The only three units I know of that have even come close to 90% are the FSP Zen 300W, Antec Phantom 350W, and PicoPSU.

Those first two are fanless, making them of limited value in most performance oriented systems (and the Antec is terribly unreliable due to poor capacitor selection), while the Pico is just a DC-DC convertor designed to be used with very low draw systems and an external power brick (so it doesn't really count because the power brick has its own efficiency profile).

To translate - just keep using the Corsair. You're not going to get much better efficiency ;)

[perfection]

Oh okay, I was thinking of the Antec Phantom 500W because of its hybrid fan design, is that unreliable too?

[Oklahoma Wolf]

Oh okay, I was thinking of the Antec Phantom 500W because of its hybrid fan design, is that unreliable too?

Same OEM, same awful cap selection, same platform.

I don't think I've recommended the 500W a single time, whereas I actually did like the 350W for a while (before I knew how bad the cap issues were). Reason being, when the fan was off it was no more powerful than the 350W little brother and when the fan was on, it was hardly phantom silent ;)

[perfection]

oh okay thanks, what is the most silent PSU you can buy? 550W - 650W would be nice, I find my Corsair is getting a bit noisy

[Oklahoma Wolf]

The problem is, anything over 600W or so is going to make its presence known if you load it up close enough to its rated output. However, Seasonic may have something a bit quieter than the Corsair, despite actually being the OEM for the Corsair.

It might also work to go way up the ladder and grab a 1kW+ unit with a 135mm fan, like the Thermaltake Toughpowers, Silverstone OP/DA1200, or Ultra X3 (the few good Ultras on the market are the Andyson made X3's). They might not get hot enough to spin up the fan much. But that's profound overkill costing a lot of money.

Not that I'm a real expert on silence, but my CWT 1200W, on which the Thermaltake 1200W is based, is inaudible as I'm typing this. It's being drowned out by the 1500RPM fan on my Thermalright Ultra 120.

[perfection]

thanks heaps Oklahoma wolf :up:

I've heard the Thermaltake Toughpowers are really good, but 1kW + unit is just to pricey.

I've been looking at the Thermaltake Toughpower 750W as its the lowest TT TP with modular cables I can buy in Australia.

I'll check out the Seasonic's too

[Polizei]

Silverstone Olympia 650w I have is dead silent, but not modular. Decathlon 650w will be the same way, just modular. Good stuff. :up: