[QUOTE=yojimbo197;2709258]The amperage thing is somewhat of a myth as explained here:
The more important part is how much of the total power is getting to the 12V rail. A good PSU will deliver 80% or more.[/QUOTE]
Umm, I’m little confused. Power equals voltage multiplied by amperage. The link explains that if you have for example, a 500W power supply - and if it doesn’t deliver ~75% of that power in the +12V rail - it should be considered as lower wattage PSU.
And in that case you might miscalculate the power supply in question to be adequate when in reality it’s not.
So staring at the PSU’s rated wattage doesn’t cut it. Voltage is constant, can’t rely on wattage - so the only thing that I can look is the rated amperage.
Example: Let’s take a 500W PSU which delivers 35A on the +12V rail (12V*35A = 420W), which equals 84% of the total power delivered in +12V rail. For argument’s sake let’s take a 800W PSU, and it too delivers 35A on the +12V rail. So the wattage in the +12V rail is the same 420W, but in this case it is only 52,5% of the rated wattage. And in reality (if you don’t have anything that draws huge amounts of power from +5V or +3,3V lines) these two PSU:s are equal in practice.
You need to think about the total draw on the PSU which is the sum of your components. Also you are forgetting about case fans, external hard drives, etc. In addition, if you are going to use the PSU longer than a year you will see degradation of the capacitors over time. There are a couple of different power calculators out there that will tell you how much wattage you need. This one is pretty useful:
Plugging in your components into it and using Soundblaster as a substitute for your audio card plus guesstimating how many fans are on your case, I get 213W, 263W recommended. So your 350W PSU should be able to handle the load allright.
Oh yeah, forgot the case fan. 2-3 watts on the 12V line should be enough for a case fan? Only possible USB device is a memory stick. And yes, I must check the caps before even thinking about using the PSU.
What you may have not known is that there can be a special sleep/idle state for Haswell CPU’s that require a PSU that can deliver very low levels of power to the Haswell and stably. It is supposedly possible to disable this idle/sleep state in the BIOS of Haswell boards, so you could potentially use your PSU. Or you could just shut off your PSU when you are finished with your computer.
All that being said, you might want to consider upgrading to at least a 80Plus Bronze or Gold PSU to save on power over the long run and avoid having to deal with workarounds for the idle/sleep state.
Yes, I read about this. It is not a problem - I don’t use sleep state and at least the HDD’s are whirring away so that should be enough load to keep the PSU up and running.
I’m still wondering about how much power (amps) is needed from the +12V line to keep things running… Manufacturers should really put power consumption figures in their products, not just vague “1 megawatt PSU is recommended” when it seems that it is grossly overrated.
If memory serves me correct, too big a PSU also hinders efficiency and targeting the 50% load mark would be good.