Any red flags before I buy these parts?

bmg50

Honorable
Dec 5, 2012
4
0
10,510
Hey, I'm looking to replace many parts in a computer I received some time ago. It'll mainly be for gaming, perhaps even some 3D rendering. I'm pretty certain I've decided on the parts I want, but I haven't built a computer (or replaced this many parts on my own) since I was in high school, so I'd rather make sure nothing sets off any red flags for you guys before I go with the buy. 

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Motherboard 

GIGABYTE GA-Z77X-UD3H LGA 1155 Intel Z77 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard 
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128544

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Graphics Card 

SAPPHIRE 100352-2L Radeon HD 7950 3GB 384-bit GDDR5 PCI Express 3.0 x16 HDCP Ready CrossFireX Support Video Card 
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202006 

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PSU 

Rosewill CAPSTONE Series CAPSTONE-750 750W Continuous @ 50°C, 80 PLUS GOLD Certified, Single +12V Rail, ATX12V v2.31 / EPS12V v2.92, SLI Ready, CrossFire Ready, Active - PFC Power Supply 
http://www.newegg.com/Product/Product.aspx?Item=N82E16817182073 

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RAM 

GeIL Black Dragon 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model GB316GB1600C10DC 
http://www.newegg.com/Product/Product.aspx?Item=N82E16820144564 
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I have a i3-2120 Sandy Bridge 3.3GHz that I picked up for a price I really couldn't pass up (and it blew the old processor out of the water), so that's the processor I'll be going with for at least a while still. I know it's a good processor, but I also know it's really not on the same level as the other parts I'm sticking in there. Any chance of it bottlenecking the GPU? 

And finally, I have a fairly large case already, but I really don't know much about it (plus I'm at work atm so I can't really check it out to find out exactly what kind of case it is). I'm wondering if I should replace it for something that I -know- will be better for cooling, instead of taking a chance on my own? I never really intended to get a new case, so if you guys think it's a must to avoid overheating then please get me the best you can find for under 100$.

Whew, that's pretty much it. Sorry for the length of the post. If there's anything I left out that will help you better answer me then feel free to ask. Thank you very much in advance!