Sign in with
Sign up | Sign in
Your question
Solved

What is Amperage?

Tags:
  • Graphics
Last response: in Graphics & Displays
Share
November 20, 2013 6:43:16 AM

I'm fairly new to computers and was wondering what amperage was? Lat year I built a computer but I couldn't get the parts I wanted because of some 24 amp on the +12 volt rail?

I have no idea what this all means so if someone could explain it, I would appreciate it!

More about : amperage

November 20, 2013 6:50:36 AM

Amperage (current) is the amount of electrical energy flowing through a circuit. See below:

http://www.wisegeek.com/what-is-amperage.htm

In a power supply, the amount of watts given for the +12V rail is found by multiplying the amps (24) by 12 volts = 288 watts. For a PSU, this is the important rail as it runs the graphics card and the CPU. That way you can work out if you have enough power for them.
m
0
l
November 20, 2013 7:02:07 AM

Voltage is how much. Amperage is how fast. So in this case it needs to be 12V "travelling" at 24A. Which is 288W of power.

You don't really need it all on one rail. The original ATX spec when this started said no rail over 18A. So you might see some PSUs that say 12v1 = 16A, 12v2 = 16. 12v1 and 12v2 not to exceed 360W (which is 30A total.). If the card says you need 24A on the 12V rail you are ok.
m
0
l

Best solution

November 20, 2013 7:11:50 AM

There are four important things in any electrical circuit: voltage (E), current (I), resistance (R), and power (P). Voltage can be thought of as the "oomph", how much "push" is available. If a circuit were a river, voltage would represent how fast it's flowing. Using the same analogy, current would be the amount of water (how wide and deep the river is.) Resistance is, obviously, the amount that the flow of electricity is impeded...dams, rocks, weirs, and other obstacles in our river. Power is determined both by the river's speed (voltage) and how big it is (current).

These factors are related to each other by Ohm's Law, which is:

E = I x R, where E is in volts, I in amperes (and here is where "amperage" comes in), and R is in ohms. If you know any two of these factors, you can determine the third.

And the relationship for power is:

P= E x I Again, E is in volts, I in amps, and P is in watts.

A power supply is "rated" for a given current...that is, it can safely supply that much current without burning out. If you have a power supply rated at 24 amps, and you have a motherboard and CPU that take, say 6 amps and two graphics cards that each need 10 amps...you need a bigger power supply! If you only know the power supply's power rating (say, 500 watts), you can still find out if your power supply is adequate. Just calculate the power used by the components...CPU 85 watts, motherboard 20 watts, graphics cards 200 watts each, and so on...and add them together.
Share
!