A lot of posts for me to respond to. Will try to keep it brief...
Originally Posted by GoLDii3
Already did,didn't show anything interesting.
Makes me wonder how can you pull off a 290 CFX with a 850W power supply,if according to your own logic,those cards can pull up to 400W. And since you have two,that would be 800W. And the rest of the system? Must be magic.
It's not about "lower capacity PSU" like you said. It's about math.
PC with i5/i7 at stock without GPU -> Max 150W
150 + 290 (Your supposed 290X TDP) = 440W
Seasonic SII12W +12V Rail wattage: 480W
It doesn't matter if it's close to the limit. 12V is rated to output 480W,it will output them without a single problem. It doesn't? Then it's a junk PSU.
Didn't show anything interesting? Ok, then.
Did my research when I chose my PSU. I don't OC my CPU and run my 290's stock because they run all my game fast enough without OCing. In that regard, I've got decent overhead. If I were to be OCing my CPU and GPUs daily, I would have gone with a 1000w unit, just for peace of mind, to have the extra overhead and know my PSU should last a long time as it's not being run on the ragged edge all the time.
Like I said before, I never said your 520w unit wouldn't work. I said it's not ideal and I would strongly recommend upgrading to something beefier for reliability and longevity sake. But do what you want. It's your system.
Originally Posted by Roboyto
TDP is not the same as power consumption. It is the amount the heat that needs to be displaced under normal operating conditions.
Just want to be certain you are aware of this.
Yes, I am aware. It's still a good value to use to estimate the actual power draw of a GPU - which quite often can actually be higher than the TDP rating.
I guess it depends on how you define "cutting it close". I don't consider "cutting it close" (running a PSU at 90%+ load) to be "OK". Not for daily use. Just personal preference.
Originally Posted by mus1mus
This PSU thing has taken a lot of replies already.
I don't wanna mention any names but it seems that the confusion is growing.
I don't understand why some would not consider spending a little extra to get a little headroom on PSU power knowing that everything in the system connects to a power supply. If that thing goes bad for overloading, chances are, it will take components with itself. Does this even make sense?
Also, people are putting too much emphasis on spending a premium on high quality units more than power ratings. Even basing calculations to what reviewers shown. Like, a certain reviewer tested a unit past it's rated output. i.e. 1000W on an 850W unit.
Some people take this and buy an 850W unit when their calculated load would be around a 1000W --even more.
Doesn't sound so healthy of a thinking for me. But then, it'll take a hard lesson to learn on something that is generally accepted truth or even myth sometimes.
Well said. Just to comment on one thing; Power ratings and quality are both important. I don't recommend people buy crazy overpowered PSUs for their systems or also only buy the best top quality platinum units, but rather a balance where power and quality to price is reasonable, relative to what you need.
Originally Posted by kizwan
That is correct but if the card is outputting let say 250W of heat, how much power do you think the card is pulling? The answer is more. You can actually use TDP value especially with graphic card as a reference for how high (wattage) PSU you should get.