Need help with Crossfiring two 6950's

[Corvid1986]

Since upgrading to a 6990 is out of my budget I've been considering crossfiring my current 6950 with a new 6950 but I have no idea whether this is truly worth it and if my PSU can actually take it.

Specs:
Motherboard - ASRock 890GX-Extreme 3 890G
Processor - AMD AM3 x6 1100T 3.30 ghz Phenom II
GFX - AMD Powercolour 2 gb 6950
Ram - G.Skill-NT 8GB (4gx2) DDR3 1333 ram (intel 1155,1156,AM3)
HDD - Hitachi Deskstar 3tb Sata HDD 7200 RPM
Disk Drive - LG Blu-Ray SATA Writer
PSU - Antec EarthWatts EA 650 Watt PSU
Cooling - A-Power 120mm 2x Ball Bearing Case Fan

I did a rough check and found that the processor and the two 6950's would hit 540 watts (probably more) which i don't think gives me much breathing room. If i need to i can upgrade the power supply but i'd be hitting close to 450 AUD for an 850 Watt if i did and well a 6990 is only 300 or so more than that. So is it worth it and can my system take it? Also, should i get a better cooling system(if i need one, may aswell get a 6990)?

 

[camster3]

Antec is a good brand, they can handle more than 650W, all good brands can.

With the corssfiring, i crossfired my 6970 recently, was ive started to have issues with microstutting. Although when it wokred, it scaled good and gave very good results

 

[FtsArTek]

I wouldn't run it on less than a 750 for long, but my system ran on a 650 Corsair for a bit until I got the upgrade.

 

[Corvid1986]

I went out and grabbed a 750 watt PSU the COrsair hx750w but i've got a problem with it.
Topic here
http://www.tomshardware.com/forum/323098-28-corsair-hx750w-pcie-plug-question

 

[JackNaylorPE]

The EA-650 Green is certified for 6950's as follows:

ATI Radeon™ HD 4870 1
ATI Radeon™ HD 4850 1
ATI Radeon™ HD 4870 X2 1
ATI Radeon™ HD 4890 1
AMD Radeon™ HD 6850 2
AMD Radeon™ HD 6870 1
AMD Radeon™ HD 6950 1
AMD Radeon™ HD 6970 1

So, no....according to AMD, two 6950's are not supported on the EA-650