What's this lead attached on my GPU?

Hi,

Looks like a floppy power cable to me.

Check markings on the card to identify it then google, you should find a manual or specsheet online,
Personally I reckon its a Pwm controller for the fan to allow the mobo control of it but I'll never know unless you get searching  
the circle connector btw is for a really old TV ariel (Co-Axial cable)
https://www.google.co.uk/#hl=en&safe=off&output=search&...(1GB%2C+DDR3%2C+TV+Tuner%2C+PCI-Express%2C+AMD+Accelerated&oq=VTX3D+AMD+Radeon+HD+6570+Graphics+Card+(1GB%2C+DDR3%2C+TV+Tuner%2C+PCI-Express%2C+AMD+Accelerated&gs_l=hp.3...983.983.0.1467.1.1.0.0.0.0.61.61.1.1.0.les%3B..0.0...1c.1.4.psy-ab.VdOoPefPx3A&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.42768644,d.d2k&fp=52e25552b949de7b&biw=1463&bih=746 shows it to be a Gfx card with built in TV tuner though so possibly that cable does more than I thought
Moto

the random lead is connected to this circle connection part, under the circle connection it says ATN, i dont think i need anything of this, i think if i plug in into the PCI slot, it'll work fine without that lead plugged in anywhere, just waiting for the rest of my pc parts to be delivered

btw i bought this card from ebay (no original packaging, just the card) i found it online and its a digital streamer edition, so yeah i'm guessing its to do with a TV ariel maybe

Does that connector have anything printed on the reverse side btw?
as you say it will work fine without that being plugged in anywhere but curiosity has me dying to know lol
Moto

after more searching i found the answer:
VERTEX3D, a brand of AMD graphics card, today launches a new series of VTX3D HD6670/6570 Digital Streamer Edition. VTX3D HD6670/6570 Digital Streamer Edition combines digital TV content with computer, using FlexiTV technology designed by Mirics.

By utilizing Window Media Center, the latest VTX3D Digital Streamer Edition can easily extend the home entertainment experience from TV to the PC. DVB-T TV signal support enable users to watch the free digital TV program on PC in HD/SD quality, allowing a casual, fun enjoyment without the limitations of a conventional TV.

i wont need this but if i did i wouldnt know where the plug this lead into without the manuel lol, at least our curiosity is solved!

Yeah, maybe the HD Audio socket? at least you aren't losing anything though and can still use the card normally  
Moto