Caporegime
Hate to say it, but the TX550M was fine for that spec,
http://www.guru3d.com/articles_pages/msi_radeon_hd_7950_twin_frozer_iii_review,8.html
The TX550M is a better class of PSU than the CX600.
The CX600 is rated at 40 AMPS.
The TX550M is rated at 45 AMPS.
Thats on the important 12V line.
http://www.guru3d.com/articles_pages/msi_radeon_hd_7950_twin_frozer_iii_review,8.html
Radeon HD 7950 - On your average system the card requires you to have a 500 Watt power supply unit.
The TX550M is a better class of PSU than the CX600.
The CX600 is rated at 40 AMPS.
The TX550M is rated at 45 AMPS.
Thats on the important 12V line.