i have a 550w PSU i wanted to buy a HD radeon 6570 2gb gddr3 it says on the page i need a minimum 400w for hd radeon 6570 and 500w greater for crossfire mode what is crossfire??
In short, Crossfire means running two of the same GPUs (is "bridged" the correct term?). Basically the power requirement increases because you're running two cards at the same time.
how much ram do i need for this gpu? i only have 1gb ram -.-
You don't need RAM for a GPU. It has its own GDDR3 memory.
Edit: Check out the system requirements at the manufacturer's website:
PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard
400 Watt or greater power supply recommended
Minimum 1GB of system memory