Will 450W PSU be enough for the following build-i5-4440, gtx 950 and 8gb RAM?

What do you mean by the 450W PSU? It is truth that every power supply has the ability to create a current at a high enough rate (since current is a flow of charge and the faster the charge moves the higher the current) to merit 450W. Let me state it in an easier way: every power supply is capable of fulfilling whatever power requirements the hardware needs. So a 300W power supply does have the theoretical capabilities to create a fast enough current to merit enough power to power 4 980Tis. Power cannot run out. There is no such thing as "enough power", because power is not a substance that can be in excess or in famine. So then, where do barriers come into play? There are three primary factors:

1) It's important to realize that power is current * voltage. Current, in computers, is the rate at which electrons flow. Voltage is the electric fields, how strong they are, which plays into effect on how much power there is. Power is energy flow. What is important to realize is that, no matter what, a power supply will always try to fulfill the "power requirements" some hardware currently needs. But how stable this voltage is is important. The current will be whatever it needs to be to make the required wattage of components. So voltage stability is important. Those 300W power supplies powering 4 980Tis - they will have dangerous and fatal voltages at that load, and kill the hardware. So how well a power supply unit regulates voltage is important, which has nothing to do with its wattage number on the label.

2) Protections. Power supplies have built-in circuitry that detects if something is wrong, such as too much current (which can cause burning or melting of internals), or an unstable voltage. What do these protections do? Shut the unit off. So the thresholds at which these protections are triggered is the next important factor for power supplies, and what makes a quality "300W" unit different from a quality "750W unit".

3) If current is too high, the power supply can catch fire. We sure hope it has well working protections. This goes along with #2 because a power supply need safety features.

Oh boy, I'm rambling on again so what can you get out of all this? It's a conclusion I came upon myself one day: labelled wattage is evil. Ignore the wattage labeling on a power supply, because there are 300W power supplies much better suited for a 980Ti than some of the 750W units out there. There is no consistency to labelled wattage, so it is a wicked value that cannot be used as a parameter of comparison.

Anyway, what are your specs?

Edit: Oops, I see the specs now. I'll recommend what I always do, a Seasonic S12ii 520W. I'm interested as to what you have come up with.