Coincido con el amigo
josssoriano
La Vapor X tiene algunas mejoras en cuanto a temperatura y un funcionamiento más silencioso.
Cita: SAPPHIRE Technology is now shipping a new graphics card in the highly successful HD 5000 series – the SAPPHIRE HD 5770 Vapor-X, delivering the same value for money performance as the standard model, whilst working at lower operating temperatures and significantly more quietly.
The SAPPHIRE HD 5770 Vapor-X is based on the latest graphics architecture from the ATI division of AMD, the second generation of GPU to be built in its 40nm process. It supports the advanced graphical features of DirectX 11, and delivers spectacular video clarity, speed and visual effects, including over multiple monitors using ATI Eyefinity.
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Dejando de lado las cosas técnicas, que en general son bastante similares, yo me decantaría más que todo por el precio.
Saludos....