Xtrem Ovrclakr :
Graphics card TDP is 145w and it needs minimum 500w Power Supply. And the main thing that we can't suggest a power supply without knowing the specifications. If he has FX 9590 which has TDP of 220w itself, then he will need at least 650w PSU. Without knowing the specifications, we can't suggest the minimum requirement of its PSU. And 400w will never power that GPU. Even if we get the lowest power consuming CPU and lesser peripherals the minimum power requirement will be around 340w and if we do some calculations, 80% of 400w is 320w. That PSU can offer maximum of 330w because no one has 100% efficiency. It goes to 84-85% at full load. So he needs at least 500w PSU but we still don't know, blwithout it's specs that how much power does that pc required.
With respect, I don't think you understand the efficiency metrics. A good quality 400W PSU will provide in the region of 400W on the 12V Rail. It will do that regardless of the efficiency. Efficiency effects what will be drawn from the wall, not the internal wattage. An 80 Plus Platinum PSU with 400W being drawn on the 12V Rail may draw 450W at the wall, with 50W wasted to heat. A very inefficient PSU may be drawing 500-550W at the wall, with 100-150W wasted to heat in the PSU itself, but both are still providing 400W on the 12V rail.
A 145W 970 + a 80W Intel CPU would actually, probably, be fine on a very good quality 400W unit. Intel burn test + furmark symultaneously might get 250-270W from CPU & GPU, leaving 100W for the rest of the system (more than enough in most cases!) to stay within spec. Any normal gaming/encoding load would likely be less.
As others have said though, a 970 + overclocked FX chip and you're in trouble.
Given OP has just laid out a solid chunk of cash for a good video card, spending a little extra on an XFX 550W or similar is a sensible option.
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