(03-06-2014, 01:50 PM)Xenosaga Wrote: Actually, a good 400W PSU will handle almost any regular, sensible gaming system (e.g. a 4570K + Radeon R9 280X) for years to come.
Seriously, people tend to massively overestimate a system's power usage and buy either overpriced PSUs that yield no advantage whatsoever or $25 750W PSUs from ebay which equivalate timebombs. If you do not have any definite plans on going SLI/Crossfire, there's no reason to go over 550W.
What about the electrical efficiency. Most power units runs with best "electrical efficiency" when having a workload of 70 to 80 percent.
Your vendor should be able to tell you the specs of your power unit.
So you have to look over the electrical loads and sum up the consumption.
(video card, cpu,...) The total cunsumption should be the same amount as 70/80 percent of the power unit output.
If your system has at a max workload a consumption off e.g. 300 watt (which is realistic looking at your components) with an powerunit which has 80 percent electrical efficency, the total consumption will be 375 watt. (300/0,8=375)
A power unit of 450 watt should do, but with an bigger power unit you have a better electrical efficiency.
Depends on what you are doing with the pc.
If you play resource costing games all day long, most time of the week, you shoud go for a bigger powerunit than 450 watt.
You're just playing frome time to time and work with the pc? Then 450w is sufficient.
why did i post this?
You got that part completely backwards. Actually, if you measure 300W "power consumption" at the wall and your PSU has an efficiency of 80%, it means that 80% of the 300W (240W) is used by the hardware while the remaining 20% (60W) are heat. That means the electrical components of the PSU actually only have to deal with the 240W for the most part, which further underlines how much we overestimate the wattage requirements of hardware. If Anandtech or so measures the power draw at the wall, you can actually substract 15-20% of that value as mere heat!
Then, this talk about efficiency is actually a pretty moot point in my opinion. Proper PSUs nowadays (80 Plus Bronze or better) have good efficiency values all across the board and fluctuate in low, single-digit percentages (e.g 82% vs 85%).
I'm just stating my opinion on this because I often see self-proclaimed experts go around and spew crap like you NEED 600W MINIMUM to power a generic, single GPU gaming system. It's plain wrong. And this false advice often leads to either paying much more than necessary or buying cheap, dangerous garbage because of a meaningless label (e.g. 600W). To conclude, all I'm saying is that a 400-550W PSU from a respected brand is the most sensible choice in regards to longevity and money spent. Again, the only exception being that you definitely plan on going multi GPU. However, in my honest opinion, multi GPU is not worth it, especially if you do it later. It involves lots of fidgeting with driver and game settings. But that's another topic.
