What power supply do I need?

Seems rather wasteful to get an i7 when on what I would assume to be dedicated graphics, especially when the benefit over the i5 is minimal and sometimes non-existent. Curious as to what you need that ridiculous amount of RAM for also.

That aside searching online for PSU calculator, or Power Supply Calculator will typically yield tools where you can select what hardware you have and it will provide such suggestions.

Using one calculator, and a few assumptions of my own a figure of 249 watts came up.

If you really are not going to be adding a dedicated GPU then a 450/550w supply will be plenty.

However should that simply be a later option then that needs will only be in part about the wattage but more about its supply requirements in terms of the cables.

Dedicated Graphics Cards nowadays do not get sufficient power from the motherboard alone and need an additional supply from one or more PCI-E cables from the PSU.

Those come in two sizes, 6 and 8 pin varieties and can vary in the numbers required.

You may require between one or three of those for a single card, and more for SLI/Crossfire.

Someone more experienced might be able to provide better advice on brands, which given my prior need to have only replaced one PSU I am ill equipped to provide.

I think a 500 watts Power supply unit should be enough

If you have no plans of getting a dedicated card than for those specs, you can easily get by with a 350 watt power supply. (which is pretty standard for core i7 systems with onboard video.)

If you plan to go with a dedicated low power card (eg if you need additional hardware acceleration bot no serious gaming, then 400 watt+ is good.

With the pricing of power supplies as they are now, it is best to just get a 600-750 watt power supply as the pricing is close and a power supply will only pull as much power as the system wants. The ATX standards also does not change often so that 1 power supply will last you probably your next 5-6 computer builds.