Look at the +12V capacity. If it's within about 92% of the advertised capacity, then that advertised capacity is likely a continuous capacity. If the +12V capacity is significantly lower, like 80% or less, then it's likely that the advertised capacity is the peak.
However, the quality of a PSU cannot be judged by this at all.
Originally Posted by FabTheZen
Thank you for the precious info. So if I decide to buy the xfx core 650w PSU to do a sli later, even just for fun, would I be sure I could sli 2 gtx 770 or something similar?
Their recommendation is for peak-rated PSUs. Multiply the recommendation by .72 to find out what the +12V capacity might be of a continuous-rated PSU. For example, 700-800 would be 504W to 576W. 504W is the same +12V capacity of some semi-decent 550W PSUs. 576W is the same +12V capacity of some semi-decent 650W units. See? :) 550-650W.
Originally Posted by shilka
No it does not all Core Edition are rebrand Seasonic S12II´s
You want two video cards for that you should go with the 650 watts
450 watts for one video card 650 watts for two
Not always. Some 2-way SLI setups can easily be powered by a good 450-550W PSU.
Originally Posted by FabTheZen
oh ok, but for example the 450w and 550w are excluded from haswell compatibility list. Well, you know what's weird? Those 2 are now out of stock, but as I said I think they'll come back soon, but their last seen price are 80,50€ for the 750W and 81,40€ (!!!) for the 650W. The prices could change when they come back, and I hope they lower down 650W's price rather than raising the 750W's XD
shilka, you mean I could sli 2xGTX770 with 650W? Anyway, if the 750W will still be cheaper when back, buying that one would give me some advantage against the 650W, like less noise, effort etc?
Don't worry about the Haswell compatibility too much:
Originally Posted by qwan456
An independent PSU or a PSU with a DC-DC secondary will be "compatible" with Haswell's C7 power state.
Lower-end group-regulated PSU may have issues with it. Basically, this power state may keep the load of the +12v rail as low as 0.05A, and the whole scare is that the load on the minor 3.3/5v rails will affect the voltage of the +12v and cause it to go out of spec (the higher the load on the 5v, the higher the voltage goes on the +12v). So when you try to take your computer out of sleep, the OVP (over voltage protection) of the PSU may trip off and your computer will not power up.
The thing is, it's unlikely that the load on the minor rail during this low power state will be high enough to cause this problem anyways, so chances are, you don't have to worry even if it is not officially compatible (the testing methodology done by Intel and such is likely tested more in a worst-case and unlikely scenario). However, if you do run into this problem, then you should be able to disable this feature on the motherboard's BIOS.
Anyway, are you going to overclock the 770s? Are you going to overvolt them for extra overclocking? What about your CPU? What are your overclocking plans for it?
Also, unless you plan on doing some insane overclocking to your stuff, like using liquid nitrogen to cool your stuff, the XFX PSUs are more than good enough for you.