Best setup 7970 OC Boost or R9 380 Nitro

[denrok]

I'm looking at getting either of these cards
http://www.sapphiretech.com/productdetial.asp?pid=F8725148-BF0B-4F6C-B98C-28BB9846F348&lang=eng
http://www.sapphiretech.com/productdetial.asp?pid=421F760D-5247-4A25-BA5D-74A7A3139CD7&lang=eng
Which one do people recommend for eth mining? The 380 looks to have lower power consumption and 4GB

What would be the best setup?
Windows 7 or Linux? BAMT? https://docs.google.com/document/d/1Gw7YPYgMgNNU42skibULbJJUx_suP_CpjSEdSi8_z9U/mobilebasic?pli=1 ?
Which Catalyst drivers
Is it possible to undervolt/overclock these cards?

I will be using an ASUS M5A97 https://www.asus.com/uk/Motherboards/M5A97_LE_R20/ motherboard with xfx 1000W PSU http://xfxforce.com/en-us/products/xts-series-platinum-full-modular/xts-series-1000w-psu-p1-1000-belx

Does anyone have a some optimal settings to use?