We can confirm the R9 270X is not a `crippled HD7950` as reported by some sources nor does it have a Tahiti LE core at its heart. It uses a redesigned Pitcairn core complete with 1280 shaders, a 256-bit memory controller with 2GB to 4GB of GDDR5 at its helm. Clockspeeds will inevitably vary between manufacturers but the reference design is clocked to a healthy 1050MHz and a memory clockspeed of 5600MHz (effective)."
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips