Will this psu work with Dual gtx465's

Solution
According to NVIDIA's specifications a single reference clocked GeForce GTX 465 has a Maximum Graphics Card Power of 200 Watts. This means that the card may draw up to a maximum of 16.7 Amps from the +12 Volt rail(s). NVIDIA recommends a minimum of a 550 Watt power supply with a combined +12 Volt rail(s) current rating of 38 Amps.

For two GeForce GTX 465 in 2-way SLI NVIDIA recommends a minimum of a 750 Watt power supply with a combined +12 Volt rail(s) current rating of 55 Amps.

Your Corsair GS800 Power Supply is able to provide up to 65 Amps on its single +12 Volt rail so your power supply meets/exceeds the requirements for two GeForce GTX 465 in 2-way SLI.
According to NVIDIA's specifications a single reference clocked GeForce GTX 465 has a Maximum Graphics Card Power of 200 Watts. This means that the card may draw up to a maximum of 16.7 Amps from the +12 Volt rail(s). NVIDIA recommends a minimum of a 550 Watt power supply with a combined +12 Volt rail(s) current rating of 38 Amps.

For two GeForce GTX 465 in 2-way SLI NVIDIA recommends a minimum of a 750 Watt power supply with a combined +12 Volt rail(s) current rating of 55 Amps.

Your Corsair GS800 Power Supply is able to provide up to 65 Amps on its single +12 Volt rail so your power supply meets/exceeds the requirements for two GeForce GTX 465 in 2-way SLI.
 
Solution

Yes. The NVIDIA recommendations have taken the CPU, cooling fans, motherboard chipset, hard disk drives, optical drive, etc into account.