PSU What size PSU for this upgrade?

I need a new PSU for an upgrade to my current rig. The new build is going to be

i5 4690K
Gigabyte Z97 board - not decided which,
AIO water cooler - Either my current H80 or the larger H110 - not decided yet
R9 270x.

I have looked at the PSU estimators which say this will need a 550 watt PSU, but I stumbled upon a video which says that I should be adding a further 150 watts on top to provide overhead which has really confused me???

FWIW, my current PSU is an OCZ Stealth2 something 600 watt which is going into my kids build which currently needs a new PSU (thought I'd upgrade my PSU instead )

I am going to be overclocking the CPU as well if this adds in anything and I am looking at either semi or full modular PSUs as well

Any advice and recommendations would be gratefully received.

 

Agreed, I expect the calculators already added the extra overhead into the equation.

 

As above, even a decent 450W unit would suffice.

 

I'd get a 600w unit, it'll give you a bit of margin and it'll still be fairly cheap. Something by Corsair, Enermax or Silverstone would be good.

 

300W would be entirely sufficient (going by Anand's total system power consumption testing with a larger overclocked i7-4960X), so 400-450W would be far more than enough for any possible overclock outside of LN2.

 

Sometime in the next 6 months I will be upgrading the the GPU from the 270x to something in the range of the 280/280x - 290/290x or Nvidia ??? - will the 550 be enough for this additional upgrade or would it be better to go for the slightly larger 600 watt?

 

Thanks - one final question. Is there any reputable brands i should avoid? And any I should consider?

I have been looking at the Cooler Master VSM650 Semi(Hybrid) Modular PSU as it seems decent and is well backed with a very good 5 year warranty. other than that one, I'm not entirely sure what brands to go for, apart from Corsair that is.

 

Easy way is just to go for PSUs with an 80+ certification.

 

a Corsair CX 500 should do alright. 80+ bronze rated, and cand be had for less than fifty quid. Or for a few extra quid you can get the semi-modular version (CXM 500)

 

thanks for the recommendation. I'll take a look in the morning.

edzieba mentioned to go for anything with an 80+ rating - Scan have some PSUs by a company called Powercool which are listed as being 80+ rated, but are less than half the price of a brand i recognise - Are these PSUS likely to be as bad i think they are without trying them or is it an OEM brand i've never heard of (not that i would buy a PSU as cheap as that as you get what you pay for)

As an example

 

It's not listed by 80+, so it looks like Powercool are telling porkies.

 

I wouldn't opt for powercool myself
http://www.jonnyguru.com/forums/showthread.php?t=8035

 

it was, as one says 'too good to be true'


Edit - I finally went for the XFX XXX Hybrid 650watt, which going by the reviews, is a rebadged Seasonic PSU
This one
http://www.scan.co.uk/products/650w-xfx-xxx-hybrid-modular-80plus-bronze-1x135mm-atx-v22-psu


And so the upgrade process begins

 

Great purchase, I've just bought a similar XFX one myself. Yep, it's a rebadged Seasonic

 

650w is what I would have gone with.