I used REALLY cheap components for my rig and I still get ~250MHash/s on my 5850. Components that I have:
- ECS DS7610 - 1 PCI-E x16 slot (I don't know if it's PCI-E 2.0, probably not)
- Athlon 64 2.0GHz S754
- 512 MB of DDR RAM
- 40 GB PATA HDD
- 350W power supply (yeah, this one is cutting edge)
- other stuff is integrated or missing
- and of course, Radeon HD 5850, costing 3x the whole thing
Whole package was worth ~$70. And it works happily!
. What I had to do to make it work:
- installed server edition of Ubuntu, and on top of it a very lightweight desktop - E17
- underclocked my CPU to 1.0 GHz. When I didn't, the whole rig would shut down after a while of mining, probably because of cheap 350Watt PSU. When underclocked, it works fine. Underclocking is done by editing /etc/init.d/ondemand file and changing the governor on line #26 to "powersave"
- plugged of CD-Rom after the installation. It can take up to 20W and I don't need it anymore.
Finally, this is how it looks like. Behold