Parece que você precisa de monitores idênticos para executar todas as três das interfaces com clock TMDS (isto é, DVI ou HDMI).
The catch here is that these can’t be independent displays, and this change is primarily intended towards enabling Eyefinity with cheap, DVI/HDMI-only monitors. To utilize clock sharing and to drive 3 such monitors off of a single card, all 3 monitors must be timing-identical, which functionally speaking almost always requires the monitors to be completely identical. Furthermore the sharing of the clock generator can only be engaged/disabled upon boot, so the 3rd display cannot be hot-plugged and must be present at boot time.
(ênfase do Anandtech)
Um ativo (não passivo) DisplayPort para adaptador DVI / HDMI permitirá que você use os monitores que você tem atualmente:
Using the DisplayPort, either with a native monitor or through an active DP-to-DVI/HDMI adapter, still allows the same fully independent functionality as before.