How to consider power supply when building a PC?

I've looked at multiple PSU calculators online and they've all given me a range around 600-800 Watts, most being closer to 800 W. However, I've looked at multiple forums that talk about how manufacturers overstate their requirements by a lot, and a lot of my parts have very low requirements. So I have 2 questions:

Does them overstating their power requirements have any effect on my choice? If so, how do I figure out which PSU I really need?
More importantly, some of my parts have very low requirements like 200 W, so if I get an 800 W PSU, will that fry my parts?

I apologize if either of those are dumb questions, this is my first custom PC

EDIT:

My likely CPU: Intel Core i7-4770k Haswell
My likely GPU: EVGA Nvidia GTX 770

Oztaco - Reinstate Monica C.

Posted 2013-12-24T07:48:43.410

Reputation: 1 305

I would suggest editing in your expected build components. Quality power supplies will list their wattage as continuous, and some as momentary. Ones with continuous load ratings are what you are looking for. Also 50C load, +5VSB > 50% efficiency, and SLI certifications are wanted. I chose an Entermax Platimax 850W for an expected 200W average 500W max and am extremely happy with the choice. – Richie Frame – 2013-12-24T09:42:26.357

Answers

It would have been useful if you had included the Processor and Graphics card in your question. Anyways, it seems like you are planning a dual gpu configuration.

More importantly, some of my parts have very low requirements like 200 W, so if I get an 800 W PSU, will that fry my parts?

No. It Won't. 800W PSU can deliver a maximum of 800Watts. If your PC is using only 200 Watts, it will deliver 200. I will not fry your parts etc.

More than wattage it is imortant that you get a Good quality PSU. Don't go for cheap ones like Corsair CX series. Go for Corsair TX750 V2 or Corsair HX750 Both units are made by Seasonic and are excellent.

makemyrig

Posted 2013-12-24T07:48:43.410

Reputation: 44

I have had very good luck with Corsair HX units, not as good with TX. – Richie Frame – 2013-12-24T09:29:11.063

Not all TX units are good tx650v2 and 750v2 are great. Others are average at best – makemyrig – 2013-12-24T19:11:03.313

It's not important that you get a good quality PSU. Get one if you like, there are advantages of course, but your system will work just fine with a cheap unit. It's most definitely not more important than power output, because your system will not work at all if the power output is too low. – Marcks Thomas – 2013-12-24T20:56:13.087

One of the dirty little secrets of the PSU market is how criminally low the output of some models are in real world scenarios. The "certification" of some cheap 600 or 700 watts was does in some shady lab at unrealistically low temperatures. Why? As a power supply gets hotter, the output decreases, so in some real world environments, the output of the device could easily be 20% lower than is advertised. Shop around and do your research, because a cheap power supply can and will kill your motherboard, CPU, hard drives, you name it...

MDT Guy

Posted 2013-12-24T07:48:43.410

Reputation: 3 683