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I'm looking for some components to build a new PC, and noticed that there are quite a few motherboards which have all three of DVI, VGA and HDMI.

I want to connect this to two DVI monitors, so my question is :

Can I use both DVI and and HDMI outputs of the (on-board) graphics of a motherboard at once?

e.g., This Asus board : ASUS M4A78 PRO ATX AMD Motherboard has all three outputs.

Additionally: Is it possible to use all three outputs at once for triple-monitor goodness?

(I'm not worried about stellar graphics performance, as I don't tend to play many games on my PC, so on-board graphics are fine)

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It's worth noting that the Zotac ION N330 mini-itx board can use both HDMI and DVI if the manual is anything to go by. Maybe this will become more commonplace in the near future :) – Legooolas Jul 26 '09 at 21:05
up vote 5 down vote accepted

I've got a Gigabyte motherboard with DVI, D-SUB and HDMI onboard and I know that doesn't allow use of HDMI and DVI at the same time.

From looking at the manual for your motherboard (which is available from the QVL page at ), the same is the case for your motherboard. You can use DVI and D-SUB at the same time, or D-SUB and HDMI at the same time, but not DVI and HDMI.

DVI and HDMI are variants of the same standards, or HDMI is a superset of DVI. Unlike DisplayPort they also require a separate clock per each connection, meaning there is a hard limit to amount of DVI/HDMI connections you can use at once. On most discrete cards the limit is 2, on integrated graphics it varies.

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I shall have to look more carefully at the manuals of motherboards I'm considering buying to see if any of them do allow this. Thanks! – Legooolas Jul 20 '09 at 12:58

This is a very specific function of your motherboard. While I can't speak for the ASUS unit you are using, I can tell you that I have seen mixed results with HP units. Some support driving two monitors, others force you to pick one and stick with it. You'll definiately want to consult your BIOS manual for more info. If in doubt, and you just really need to have more screen space (but not the gaming prowess of a GPU), either get a card with multi-monitor support, or get one of those new USB-Video driver boxes (they're fairly cheap).

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If the motherboard supported multiple monitors (built in Dual Head graphics), I would expect that to be highly advertised on the product's marketing material / web site. – pcapademic Jul 20 '09 at 12:30

it depends on the number of provided sync clocks. Most common is 2 out of all provided connectors, one digital and one analog. But there are also solutions out there where either only one output at once is supported or two out of all available.

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