Hi, this is my first build and iv got everything but a power supply. so far iv got : MSI 790X-G45 Mother Board
AMD Athlon II X4 640 3.0GHz
G.SKILL Ripjaws Series 4GB (2 x 2GB) DDR3 1600
EVGA NVIDIA SuperClocked GeForce GT 240 512MB GDDR5
Western Digital Caviar Blue 500GB 7,200 RPM Hard Drive
Cooler Master Storm Scout Mid Tower Case
1 CD-RW/DVD-RW Drive
120mm Red LED Fan
140mm Red LED Fan (fans come with case)
any one got a idea for a power supply. im looking for something of good quality, not loud and not to much $.
The only way the 550W is a better choice is if he is planning on getting a bigger card in the future.
Remember the more load a psu carries the more power it loses and the more heat it produce
If you want to get technical, remember that the more a PSU operates on the edges of its abilities the lower the efficiency. A 550W PSU won't be very efficient power only 200W of computer. A 380W will be more efficient at it however. (half of its power vs 1/3rd.) Add in that the 380W is cheaper, and it doesn't make a lot of sense to get such a large PSU.
Labeled the power supply with peak wattage, which can only be achieved during some seconds and, in some cases, in less than one second.
For some manufacturers sure. Antec and Corsair don't do that. Their PSUs can actually output what they claim.
A Power supply achieves its highest efficiency when delivering between 40% and 60% of its maximum capacity. Efficiency is also higher when the power supply is operating at 220 V.
No argument here, other then I think the range is closer to 40-75%. I'm also assuming we are both assuming he is in the USA, so no 220 option. I find it odd however that you bothered to point this out. As I already stated a 380-400W PSU will be at 50% of its capacity with the mentioned setup. This is in the range that you pointed out. Buying a 550W PSU puts it close to 1/3rd, actual math puts it at 36%. This is below the range you pointed out. As I said, a 380-400 PSU (like the 380W Antec or the 400W Corsair) is all you'd need.
I'm not sure why your pushing the 550W so hard. We are talking about a 95W CPU and EVGA superclocked GT240 doesn't have a 6pin plug so it has to be less then 75W. Which means together you are looking at 170W. Here is a review where the whole system including the i7 975 uses about 200W at load.
Seeing as the 640 consumes less power then the 975, the load for this system would be even less, making the 380-400W PSU and even smarter idea. The only way your idea makes sense is if the PSU can't output 200W, or if he is planning on a bigger card in the future. As far as we know neither condition is true.
BTW, if you think the Antec 380 can't output 380W, I suggest you start reading more PSU reviews. Its a quality unit I assure you.
The sample reaches just 78% efficiency at 10% load, but at all other loads it's above 80%.
That includes where its 86% at 50% of its power, and its 81% at 110% of its power. 380W + 10% = 418W. Thats right. this PSU can even exceed what it should be capable of. It would have no problem outputting 380W for hours on end while you game. And before you say something, thats supposed to be at around 50c
BTW, I don't think I stressed this point enough. At 115 the efficiency is lower when compared to 230. You stated however that "that amount will be even lower", which is false. 230 or 115, a 400W PSU should output 400W. Period. I would think that an "electrician finished my degree in heavy current electrical" would know that.
Personally, I wouldn't put less than a 650 watter in any system....you might have a low power GFX card today, but why limit yourself down the road when an extra 20 bucks will let you power almost anything. And, as was said before, efficiency peaks at 50% load.....so a 325 watt draw, has you at peak efficiency point which should easily recover that $20 over its life
hats just my explanation why I advised that psu. its the pw choice he can go for the 400 or anything above only difference will be he will have less headroom. Anything from 550 under he will have to go out and get one again im afraid at the next upgrade
jeez dude stop posting stuff you dont know about! electrician or not, you need to stop taking that 40-60% thing so seriously, just because a psu efficiency usually peaks at that level does that mean that the maybe 1% gain you get from that will actually make a difference to your power bill or the environment!