Which PSU - 650 or 750 watt

Qtec

Hi Folks
I need advise from some of you hardware experts here
I'm looking for a new PSU and am getting the Corsair AX650 (€140 from Elara) or AX750 (€165 from Elara) but am unsure which one would be most suitable.
My PC spec:
CPU: AMD Phenom X6 1090T
MB: ASUS M5A97 Pro
Ram: Corsair Vengeance 16GB 1600MHz
GFX: Zotac Nvidia 470GTX
HDD: 3x Samsung F3 1TB
SSD: Samsung 830 256GB
DVD-RW: 2x Samsung??
Fans: 3x Artic Cooling 120mm
USB: Wireless network dongle
I'll probably upgrade my graphcs card over the next couple of years so the draw of wattage from it will increase in time.
I wont overclock nor use SLI
I've checked online PSU calculators from Newegg to Coolermaster to eXtreme to ASUS
They report that with my 470GTX I need between 550 to 680 Watts and if put in the 590GTX this increase to 670 to 870 Watts
People seem to suggest that online PSU calculators overstate the wattage needed.
I dont want to buy the 750w if its not needed and maybe the 650w would be more efficient ie cost less to run under my load over time.
So what would you recommend I buy?
Cheers
Q

Monotype

Techpowerup say that the 470's got a maximum of 232W. This is with a high stress testing so it would typically peak out at 171W.
Many sites will quote the power consumption including an existing system and include the PSU inefficiencies as they measure it at the plug socket.

A stressed 1090T appears to be <250W, including a graphics card and measured at the power socket.
http://www.tomshardware.com/reviews/amd-phenom-ii-x6-1090t-890fx,2613-13.html
http://www.anandtech.com/show/3674/amds-sixcore-phenom-ii-x6-1090t-1055t-reviewed/10
... actual power consumption is likely to be a fair bit below 200W.

Realistically, I think that when you add your hard drives, you could get away with 550W even with some overclocking.
You certainly don't need a 750W PSU anyway.

There's cheaper PSUs around than that - is it being modular as well as the gold rated efficiency both essential?

Qtec

Thanks Monotype.
Good to know that I dont need the 750w.
The only thing that is going to increase my power consumption in time is upgrading my graphics card so I choose the 590GTX as a benchmark for the future
So with that in mind ... am I still OK with the 650 watt?
It mad ...
http://support.asus.com/powersupply.aspx says I need 800w with the 470GTX
and http://images10.newegg.com/BizIntell/tool/psucalc/index.html says I need 680w
and with the 590GTX they say that I need 1000w and 870w!

I know the Corsair is expensive but their RMA service is good, the psu is built by Seasonic, is Gold rated and has a 7 year warranty, hence a bit of future proofing my wattage needs

So I'm OK with the 650w!?

Monotype

There's so many crappy PSUs going around that they're going to overestimate the amount that you need. A crappy 650W could be only as good as a decent 400W (as well as other unwanted side effects of instability etc).

These PSU calculators are a bit better
http://extreme.outervision.com/psucalculator.jsp
http://www.overclock.net/t/1140534/psu-calc-final-release

The GTX 590 is hardly a fair card to be looking at - it's a dual GPU card so of course power consumption will be very high. Even so, a good 650W like the AX should be enough for it.

Graphics cards having been taking a turn in efficiency and reducing power consumption. Take a look at the power consumption of the 7970:
http://www.techpowerup.com/reviews/AMD/HD_7970/26.html
It's well below the GTX 580 and it's a fair bit more powerful on average.

Serephucus

I'm sure you weren't going to, but don't touch the 590. It's a horrible card, in terms of price, performance, heat, and power consumption. A 7950 or something similar is your best bet. If you can wait a couple of weeks, there will also be a 670 and 680 on the table.

uncle_sam_ie

I have the AX750, it's an excellent PSU.
Cheaper here, http://www.komplett.ie/Komplett/product/power_supplies/20053551/corsair_professional_gold_ax750_750_watt/details.aspx

dan_ep82

Im using the TX750 (non modular) and have no problems just for example

Phenom II 1090T @3.7GHz
Asus Crosshair Formula IV 890FX
Sapphire 6870 crossfire
8GB G.Skill Ripjaw 1333mhz
64gb ocz agility
500gb 7200rpm sata
1tb 7200rpm sata
1x DVD-RW drive sata
5 fans

Personally if you can afford it I'd go for the 750

Qtec

Well guys thanks for the info

It seems like everyone has a 750w!
Well, I went ahead and bought the AX650 so I've 7 days to return it unopened and get the 750w if people convince me its needed.

Good words on the 590gtx Serephucus and I suppose grfx cards will get more efficient in time