amd radon 6850 not detecting 3rd monitor

Hi revzillia,

Check your specific card but most 6850s have one DVI-I port and one DVI-D port. The DVI-D port will not work with a DVI->VGA adapter because it doesn't pass the analog signal like the DVI-I port does. You need to look at your specific card and its reference matieral to determine its exact display configurations.

If you want you can link the exact card's make and model and someone can tell you the exact configuration required for three monitors.

Since your monitors only accept VGA, depending on your card's ports, your best choice is probably:
1) DVI-I->VGA
2) Active MiniDP->VGA
3) Active MiniDP->VGA

The above assumes you have two miniDP ports.

Also - since you are planning the same configuration using a couple 6970s: Check the configuration options and DP port sizes on the 6970s you are planning to buy (or have bought). My older 6970 (non-reference Asus directCU version) has full-sized DP ports (NOT miniDP). Most of the other ones I see being sold today use miniDP ports.

Since you are likely to be purchasing adapters, make sure you don't end up with a bunch of the wrong size DP adapters when you put in your 6970s. If you have yet to purchase your 6970s get the ones with miniDPs since miniDP seems to be the norm now (All the 7xxx series have them).