ReNew graphics card fuses to cooperate - NO POST/BOOT with 100% FANS

Plugged in my shiny new fanless Sapphire HD5450 into a completely fresh install of windows with all relevant drivers. (I used the intergrated video up until this point.) To my dismay, I turned on the machine to hear my cpu fan running at full pelt and a strange clicking noise rythmically repeating itself, with no post or bios boot. Intrestingly, my old Geforce 8800GTS will work perfectly and even more worring: when the 4 Pin Power Connector to the motherboard is disconnected during the 'phantom boot loop' the clicking will stop, but there is still no progress made. The machine is however sending out signal to the monitor, but neither the new card or intergrated graphics show anything other than black. I tried installing the drivers and then putting the card in, but alas this had no effect. Is there any reason for this? Bad card? Incompatability with my mobo? It has to be one of the two, because the machine works perfectly otherwise. I am going to test the card in another PC this weekend if the weather permits.

Thanks for reading fellow Tom's Hardwear-ers