Graphics card making hum noise after ssd install (amd radeon hd 6950)

Hi

The issue is gpu related, but il let you know what i done first. I have installed ssd into my system and put windows 7 onto it and i used a hdd for my files, pics, etc, once i installed it though there was a funny noise like a humming constatly going up and down kind of sounds like something working but it wasnt there before hand.

After a while of taking things out i discover when i take out graphics cards (amd radeon hd 6950 crossfire) the noise is gone, the noise does sound like there just working but its annoying as it wasnt there before ssd and ive made sure all wires are connected to gpu correct and its firmly in position and all screws are in firm, all the software is up to date for it too.

I don't understand why they are making this noise, if the pc has been on for a while (about 15mins) then itl stop making noise but if i start a game itl come back and stay on for 15 after im off the game.

Does anyone have any ideas why they are making this noise?? I've tried it with just one and the noise isnt as loud but its still noticeable.

Specs of pc if that helps:

intel i7 2600k
16gb ram (bit over the top lol)
asus p8p67 pro motherboard
amd radeon 6950 crossfire
850w corsair psu
intel 520 ssd(120gb)
wd 1.5tb hdd

thanks in advance guys