Are all DP cables usable in both directions?

Hardware Other Hardware
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I have a PC with DP full size output, where my monitor has 2 DP inputs, one full size, one DP mini.

My old GFX card had mini DP outs so I bought a mini DP to DP cable, and that worked fine. With the new card using full size DP, I used a normal cable, which works fine. But if I use the old cable in reverse direction (DP in GFX card) and mini DP in the monitor, it does not work. The monitor keeps switching between black screen and ‘no input signal’ message.

If I look at the mini DP to DP cables on Amazon, they state these only work from miniDP to DP, suggesting that the other direction does not work. But from Wikipedia, I gather mini DP to DP is just a straight connection, with no components in between, and all pins passed through.

So, could someone please clarify? Also, if they are only usable in one direction, how do I connect to my mini DP input on my monitor - any cables you can suggest? Thanks.

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A lot of DP cables are directional especially the ones that aren’t the same in both ends, usually those who are directional have labels such as “Source” on the input end

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The dongle is directional, the cable it’s not. Unless there is any special shielding into the cable (usually there’s specific shielding from the source side) they’re not directional if they’re copper. Sometimes even copper cable with special shielding on one end don’t cause such issues if they’re plugged in backwards.
Only fiber cables are directional because the fibers are made such that the light traveling through it can only be reflected if it travels form one end to the other and not vice versa (it get’s reflected back basically).

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Thanks both for your swift reactions. So it seems some cables at least will be directional. I’ll have to find another cable then, suitable for my needs. On Amazon.de I could only find those for Mac use, i.e. the mini DP on the source end.

Does anyone here know of one where source is DP and target mini DP, please let me know. The shorter the better (50cm would be enough, but I’ll take longer if shorter ones are not to be found)

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couldn’t you just use a Display Port to display port cable now?

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I’d like to also hook up a NUC, which uses a USB-C to DP cable. So the DP port is taken on the monitor. An alternative would be a KVM, but since my post asking about that does not (yet, hopefully) yield any useful information, I’m looking into this way to hook up both PCs, if I can get it working it will be cheaper too.

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