Avoid Visiontek like the plague!
They don't honor warranties, their customer service is almost non-existent, and they are flat out incompetent in their service department.
I have a Visiontek 3870 that kept on corrupting and crashing in shader intensive DX10 games. I first thought it was the fan issue and updated the BIOS, then I plugged in the fan directly to 12V for full speed -- no dice. Finally I sent it back to Visiontek. After nearly four weeks with no emails from them, it came back with a letter saying they could find no problem "after extensively testing it for 36 hours." Of course the exact same problems remained, so I sent several, much more emphatic emails where they finally agreed to exchange the card. I ship it back. Three weeks later, again with no email communication from them, I get the same card back, same bullshit letter, only this time they "upgraded the BIOS." Arrrrrgh! Assholes!!! $36 in shipping/handling fees and my card still doesn't work.
Finally I took matters in my own hands, voided the warranty, and replaced the heatsink/fan with a VF900-cu. Guess what? No more problems! Plus, instead of a lousy 800/1200 overclock, I now get 891/1261 and temps stay cool.
Avoid Visiontek like the plague! Go with a reliable manufacturer like ASUS or Gigabyte. Even though their warranty period is only three years, at least they honor it.