DisplayPort -> DVI Adapter, Active or Passive?

Question

I read somewhere that you only need an active adapter (usb powered) if you want resolutions greater than 1920x1200.

I also heard from someone that you need it when running triple-monitor because more than two displays drains too much power.

So to connect a 3rd monitor @ 1920x1200 to my video card's DisplayPort Port, do I need to spend the extra $100 and buy the active adapter?

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Hardware

• VCard: Sapphire Raedon 5770 1GB DDR5
• Monitor 1: Samsung Syncmaster T240HD (Hopefully using Display Port Adapter for this one)
• Monitor 2: LG 21" Widescreen (Can't remember exact model)
• Monitor 3: Samsung 17" 4:3 (Can't remember exact model)

Answer 1

See this post on Coding Horror and the superuser question that he asked

Answer 2

I have purchased the active adapter know. The passive adapter as I understood it is used in situation where the processing that is required is done by some other device (such as potentionally the graphic card or the monitor itself in some types)

I do believe that is the case, you should / must purchase the active adapter. It would be nice if you actually posted your card type so someone could answer that with more precision. I also do not think it is only resolution related I have 1920x1200 and still use the active one.