Amm..NO. AMD rates the Radeon HD 5770 for 18W of power consumption at idle and 108W maximum board power at load. The gtx460 is rated at 20-30w at idle if i remember right and 160w at maximum load.
If you want to go sli, use the 6pin PCI-E power connectors from your PSU, one for each card and use the adapters that came with the cards for the second connection.