So I know this is an old pc but I want to blow some new life into my dell xps 700. So I already installed 2 dimms of 2gb running at 800mhz and it worked. But I recently got a good deal at ddr2 ram. So I bought 4x2gb sticks of Corsair XMS2 DHX CM2X2048-6400C5DHX. So this is also 800mhz but seeing that the dell xps 700 officially doesn't support 800mhz pc6400 ram, wil this work? Please anwser that would be greatly appreciated.

SPECS:

Dell Xps 700

Core 2 quad q6600

2x2gb ddr2 800Mhz 

Nvidia gt440

250gb hdd

Creative 460 sound card