Deste artigo: Microsoft Windows Vista & ReadyBoost: Faz diferença?
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What many people failed to realized is that newer PCs, with quick hard drives like the Western Digital Raptor (for example) don't necessarily see the same impact from ReadyBoost as first thought. It's really only older computers, which have been upgraded to Microsoft Windows Vista but barely meet the minimum operating system requirements, that potentially benefit from ReadyBoost.
ReadyBoost makes a bit of a difference when the system has 512MB of memory, but it's nothing to write home about. If you're at the minimum end of PC infrastructure, ReadyBoost may make things a bit more bearable but you'd be better off upgrading system memory to at least 1GB RAM.