Running CRT monitor with DVI dongle

[imported_PrinceGaz]

An increasing number of graphics-cards have dual DVI connectors instead of one 15-pin VGA and one DVI. At the moment I have a card with one VGA and one DVI output, and drive a 22" CRT from the VGA output and use 1600x1200 @ 100hz.

If I got a card with two DVI connectors and connected my monitor using a DVI->VGA dongle, would I still be able to run it at 1600x1200 @ 100hz or would I need to drop the refresh-rate to an unacceptable 75hz which is the maximum a digital single-link DVI can output?

I assume the dongle is taking the signal from the analogue (DVI-A) pins of the DVI-I connector, so does that allow it to run at the full range of refresh-rates and resolutions supported by the card's RAMDAC, including those that exceed the bandwidth of the digital single-link (DVI-D) pins? If it doesn't, then these dual DVI cards are a serious problem.

 

[Matthias99]

I don't know when 75Hz became 'unacceptable', but, AFAIK, this should work. The DVI bandwidth restrictions should not apply to the analog out from the second RAMDAC (which is bypassed when using DVI).

 

[uOpt]

I always run dual-head with one DVI->VGA connector and one direct VGA.

Even though I run 1600x1200 and sometimes higher I could never notice a difference. Seems to me the DVI->VGA converters are not a limiting factor at all.

As a matter of fact, the VGA port on your graphics card need something like it anyway, and with more space in the external connector they might even do a better job. In a word: not a problem.

 

[imported_PrinceGaz]

Thanks for the replies, I'm glad that the dual DVI cards shouldn't be a problem as I suspect they'll soon become the norm for high-end cards.

As for 75hz being unacceptable, it is for me. Remember I'm talking about a CRT here. Everybody's eyes differ but the minimum I can tolerate for an extended period is 85hz, and 100hz is a lot easier on the eyes. You just have to ensure you've got a graphics-card with decent output circuitry and use a good quality monitor cable to minimise signal degradation when running high resolutions and refresh-rates.

 

[Chudilo]

I notice the image blinking on everything up to but not including 75.. Thus I usually keep it at 85 at least.