TheTechLounge posted a review on the Sapphire Radeon HD 4850 512MB Toxic Video Card

This is the ATI counter-point to the 9800 GTX+: Sapphire's Toxic HD 4850. It may be alone, and it may not be more power-friendly, but it's, ahem, wickedly fast. The icing is that it doesn't really cost more than other HD 4850s--sure, it's on the high side, but it's still cheaper than a 4850 and a Zalman heatsink. The astounding thing is how closely the Toxic keeps up with an HD 4870, cards that cost close to a hundred dollars more.

Sapphire Radeon HD 4850 512MB Toxic Video Card Review