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Here's the "dongle" you want: https://www.amazon.ca/StarTech-com-DisplayPort-DVI-Adapter-Passive/dp/B0035PS57C
Doesn't have to be the Startech one. Startech is expensive, but they do have solid quality.
Then it's probably your adapter.
I recommend these StarTech adapters to customers that have a DisplayPort GPU and DVI monitor. They work great.
Okay, look at my setup here:
The first photo is a picture of a DVI to Displayport adapter see this link for product specifications from amazon and if you want to buy:
the second photo is a picture of a cable that doesnt have an adapter, as its built in the cable itself. A Male-To-Male DVI to HDMI cable. Makes things easier not having to deal with adapters:
Just remember that there are limitations everytime you change the "default" output / inputs of your monitors if you don't use the ones intended for. For example, the DVI to displayport only allows resolution up to 1980x1080 (the one I purchased at least) I am sure there are other ones which better resolutions but the price you pay also will go up.
If you dont care about resolutions, etc then pick either one ;)
3D Vision/Active 3D with a 3D monitor.
personally i use these at home: http://www.amazon.com/StarTech-DP2DVI2-Display-Adapter-Converter/dp/B0035PS57C/ref=sr_1_4?ie=UTF8&qid=1443027765&sr=8-4&keywords=DP+adaptor
You can get a displayport to dvi adaptor.
full size dp.
Here is an example of one for DVI