Same thing happens to me with my 5770
. I pin pointed the noise, for me its the HDD.
So I did a test I thought the HDD wasn't getting power first (because the GFX card has two power connectors) so I didnt use the one that powered the HDD unpluged the CD-ROM drive and and used the spare one, still that mysterious ticking noise continued XD.
So I have stil now answers but when I do I'll post it on this forum.
Till then cyas
Edit: Oh and I have the AMD Athlon x2 2.8 ghz, 2gb DDR2 kingston RAM, M61PME-S2 mobo and 550 watt power suply.