What PSU should i get?

Some claim that it uses inferior capacitors, but I have yet to find a credible source that backs this up. With that said, I can tell that you care about your PC and it's PSU simply because you chose an upper level PSU to begin with. If you REALLY want to step it up, please do consider the AX860i from Corsair. This is the PSU that I chose for myself. Before you scratch it from consideration because of it's price, do yourself justice by looking at the quality and features that make this PSU up.

First, it's the only digital PSU on the market. This means EXTREMELY tight voltage regulations, which equate into better component life.

Second, it is 80 Plus Platinum rated. This is the highest that a PSU can receive. At no time will it offer less than 92% efficiency.

Third, it delivers this power up to 50C in temperature. This is an industry leading stat as well. Many PSU's are limited to 30C. Your fan doesn't have to run non-stop to keep it cool, making your build much quieter. It even has a "zero RPM" feature. If you are using less than 1/3 of the capacity of the PSU, the fan doesn't even run at all!

Fourth, it has a 7 year warranty. This may as well be lifetime, because no one into gaming keeps a rig longer than 7 years.

Fifth, it is Corsair Link compatible and comes with a Corsair Link module. The Corsair Link software is available as a free download from Corsair's site. CL allow you to monitor and tweak basically everything that you can imagine within the computer.

If you have any more questions, please ask! I'll be happy to take the necessary time to help.

Here is the link to the AX860i on Amazon.com:

http://www.amazon.com/Corsair-Professional-Digital-Platinum-AX860i/dp/B00A0HZNDW/ref=sr_1_1?s=pc&ie=UTF8&qid=1396213789&sr=1-1&keywords=AX860i

Duly noted! Well, as I said earlier, people have talked down on the RM series, but I swear that I have yet to see proof, either in a review or otherwise. As for me, I just don't see a huge flaw in the RM series and wouldn't hesitate to run it on my build. But if you don't want to "roll the dice", the HX series by Corsair is also very good. It also comes in a 650w design. Here is a link to it:

http://www.amazon.com/Corsair-Professional-Certified-compatible-Platforms/dp/B002LVUPZQ/ref=sr_1_2?ie=UTF8&qid=1396216065&sr=8-2&keywords=HX+650

The XFX Pro Series is one of (if not the only) that I would truly want in my machine other than a Corsair PSU. You chose the best when you decided to go with Corsair.

I have something that you will really benefit from. Please forgive me for it being so lengthy, but this is a VERY useful tool when PSU shopping. It lists them in 5 "tiers", with tier 1 being the best and tier 5 the worst. The definition of each tier is listed at the top, and nearly every brand name PSU and model is included in this. I would recommend only a PSU in tier 1 or 2. Take your time and look over this. It is very valuable when determining a good PSU.

Tier Breakdown:
Tier 1 provides the best quality power, great for overclocking, super high-end systems, and bragging rights.  The best of the best. Very good longevity. 
Tier 2 offers very good quality power output, and great reliability.  Highly recommended for use in new systems. 
Tier 2b contains units that almost made Tier 2, but may not have quite as good quality output(still very good), or may not last as long.  Recommended for systems not expected to run 24/7 for several years. 
Tier 3 power supplies fully meet all ATX requirements for power output quality, but don't have as good of power output quality as above tiers. No reason to replace one if you have one, and they're still good choices for most systems. 
Tier 4 units may have some problems, such as being unable to deliver rated power at higher temperatures, or being slightly out of ATX spec on power output quality.  Not recommended to buy except in situations where you will not be stressing it, or expecting it to last for more than a few years.  If you have one, you can probably keep using it unless you're experiencing problems. 
Tier 5 power supplies are NOT RECOMMENDED.  If you have one, you should strongly consider replacing it ASAP.  These can damage your computer, and often cannot put out the power that they're rated for. If a brand name is listed here, then all models from that brand name are considered to be Tier 5, except for those specific models listed above. 

-----x-----x-----x-----x-----x-----x-----x-----

Tier 1 Brands - The Most Powerful And Stable Components On The Market. 
Antec Signature
Antec High Current Pro -1200w
Antec HCP Platinum 1kW
Cooler Master V series 700, 850, 1kW
Corsair AX
Enermax Galaxy
Enermax Revolution
EVGA SuperNova G2 1000W and 1300W
Kingwin Lazer Platinum
PCP&C TurboCool
PCP&C Silencer Greater than 610 watt
Sapphire Pure
Seasonic X-Series
Seasonic S12D/M12D
Silverstone ZF (Etasis 85/75/56)
Seventeam ST Greater than 600w (SSI, V2.91)
Silverstone OP/DA Greater than 700 watt
Silverstone ZM
Ultra X3   Greater than 1000 watt
XFX Black Edition
XFX XXX Edition
Zippy/Emacs SSL
Zippy/Emacs GSM
Zippy/Emacs PSL
Zippy/Emacs HG2
Zippy/Emacs HP2

Tier 2 Brands - Top Quality components With Top Notch Stability - For Those With Price/Availability Issues With Tier 1
Antec Neo HE
Antec High Current Gamer Series
Antec EarthWatts  greater than 700 watt
Antec TruePower Trio
Antec TruePower Quattro
Antec TruePower New  --  750w
Akasa PowerGreen 80+
CoolMax CTG-750 watt/850 watt/1000 watt
Cooler Master Ultimate/UCP
Cooltek CT
Corsair GS600 / GS800
Corsair HX
Corsair RM 550
Corsair TX
Corsair VX
Cougar SX700 and GX700
Enermax Liberty
Enermax Infiniti
Enermax MaxRevo 1350
Enermax MODU82+
Enermax Platimax (600, 750, 850, 1.2K)
Enermax PRO82+
Enermax PRO87+ (500w + 700w)
Enermax Triathlor (550, 650, 700)
Enhance ENP-GH
Fortron (FSP) GLN
Hale82-m 650-750w
iStarUSA PD2
iStarUSA PD3
LEPA G500 
OCZ EliteXStream
OCZ Fatal1ty
OCZ GameXStream  less than 1000 watt (only if manufactured in December 2007 or later)
OCZ StealthXStream 400 watt
OCZ StealthXStream 2  greater than 700 watt
OCZ Modstream (only if manufactured in December 2007 or later)
OCZ EvoStream
OCZ ProXStream
OCZ Z(t)(s) Series Less than 1000W
OCZ ZX 850w
PC P&C Silencer less than 610 watt
PC P&C Silencer MkII
Rosewill Capstone (450, 750)
Rosewill Fortress
Rosewill Hive (550, 650)
Seasonic G series
Seasonic S12
Seasonic M12
Seasonic Energy Plus
Sentey Golden Steel Power 850w
SevenTeam ST less than 600 watt
Silverstone OP/DA 700 watt or less
Supermicro/AbleCom
Thermaltake Toughpower greater than 600 watt
Thortech Thunderbolt Plus 800w
Topower Powerbird 900w
Xclio StablePower
XFX Core Edition
Xigmatek MC
Xigmatek HC
Ultra X3
Ultra X-Pro
Zalman ZM less than 1000 watt

Tier 2b - Tier 2 units which have either lower longevity or slightly lower quality output.  Still well within spec, and are good units. 
ABS-Tagan ITZ/BZ less than 1000 watt
Antec VP (350, 450)
BFG 800 watt
Cooler Master GX 80 Plus 450W
Cooler Master Real Power Pro >greater than 800 watt
Corsair CS
Cougar S700
Enermax NAXN-82 550w - 750w
Hiper Type-M >greater than 650 watt
Hiper Type-R >greater than 650 watt
Huntkey Jumper
Kingwin Lazer Gold
LEPA B650, B850
Mushkin Enhanced
NZXT HALE
OCZ PowerStream
OCZ StealthXStream <less than 700 watt (only if manufactured in December 2007 or later)
Rosewill Green 630w
Silverstone EF
Tagan U95
Tagan U25
Tagan U15
Tagan U22
Topower Powerbird 1100w
Xclio GreatPower

Tier 3 Brands - Power supplies fully able to meet ATX specs, although closer to the edges of the limits than higher tier units.  Still solid units. 
Acbel Polycom
Akasa PaxPower
Akasa PowerPlus (>greater than 500 watt Models)
AMS Mercury
Antec Earthwatts >greater than 700 watt
Antec Basiq
Antec Phantom
Antec TruePower III
Antec TruePower II
Antec TrueControl II
Antec NeoPower 480 watt (Old Model)
Athena Power Space Shuttle Series
Be Quiet Dark Power Pro
BFG ES
BFG LS
Channel Well
Cooler Master Real Power Pro <less than 800 watt
Cooler Master iGreen
Cooler Master Silent (and gold) Pro
Corsair CX Series
Corsair RM750, RM850
Enermax Maximum Plus
Enermax Noistaker II
Enermax Noisetaker
Enermax Whisper II
Enermax CoolerGiant
Enhance ENS-G
Epower Xscale
EVGA SuperNova NEX B 500
EVGA SuperNova NEX G 750
EVGA SuperNova NEX 1500 Classified
Fortron (FSP) GLC
Fortron (FSP) THN
Fortron AX
Fortron HLN
Fortron PFN/PN/PA
Fractal Design Integra R2 750 W
Kingwin Lazer
Kingwin Mach 1 (the negative 12v rail may go slightly outside of spec in some loading conditions)
LEPA G900
NorthQ
OCZ ModXStream (rated for 40° C)
OCZ Z Series 1000W
Rosewill RP 2 (temperature sensitive)
Rosewill Xtreme/RX
Seasonic Super Versatile
Sigma SP
Silverstone F
Sparkle FSP
Spire Rocketeer V/VI
Sunbeam Nuuo
Thermaltake Litepower
Thermaltake Purepower RX
Thermaltake Toughpower <less than 600 watt
Topower 1000w Gold
XG Magnum
X-Spice Kira
Zalman ZM 1000 watt
 

Tier 4 - Not Recommend for stressful situations.  May not be able to put out full rated power above room temperature, and may slightly fail to meet ATX specs. 
Aerocool
Asus Atlas
BFG 1000 watt
Cooler Master eXtreme (only use 75% of labeled wattage)
Cooler Master GX (except 450w)
E-Power
Futurepower
Hale82n 650w
Hiper Type-M
HIPRO
Masscool
MGE XG
Mushkin HP
NorthQ 4775-500S/BU
OCZ Modstream (if manufactured before December 2007)
OCZ GameXStream <1000 watt (if manufactured before December 2007)
OCZ StealthXStream (if manufactured before December 2007)
OCZ GameXStream 1010 watt (essentially a 850watt power supply)
Scythe Kamariki
Sigma Shark
Sintek
TTGI/Superflower
Ultra Xfinity
Ultra X2 <less than 700 watt
Ultra XVS
Xion Real Power PowerReal

Tier 5 - Other than the units listed above for any of these brands, NOT RECOMMENDED.  Replace ASAP if you have one. 
A-TOP Technology
Apevia
APEX (SUPERCASE/ALLIED)
Aspire(Turbo Case)
ATADC
Athena Power
ATRIX
Broadway Com Corp
Coolmax
Deer
Diablotek
Dynapower USA
Dynex
EagleTech
FOXCONN
FSP Everest
HEC Orion
Hiper Type-R
Huntkey
I-Star Computer Co. Ltd
In Win
JPAC COMPUTER
Just PC
Kingwin Inc.
Linkworld Electronics
Logisys Computer
MGE
MSI
NMEDIAPC
Norwood Micro/ CompUSA
NorthQ
NZXT
Okia
Powmax
Q-Tec
Raidmax
Rocketfish
Rosewill
SFC
Shuttle
Skyhawk
Spire Coolers
Star Micro
STARTECH
Thermaltake Purepower NP
Thermaltake Purepower RU
Thermaltake TR2  (and TR2-RX)
TOPOWER TOP
Ultra X-Connect
Ultra X2 >greater than 700 watt
Ultra LSP
Wintech 
XION
YoungYear
Zebronics