HP LP2465 reacting badly on DisplayPort connection from AMD RX 6600 XT?

[Nezerol]

I previously used an AMD RX 570 which had a dedicated DVI slot. I recently upgraded to an AMD RX 6600 XT, which has 1 HDMI slot (I already use it for another HDMI monitor) and 3 DisplayPort 1.4 slots. I figured, I need to obtain an DisplayPort to DVI cable. No problem. Obtained it today, and tried it out. Uh... Green screen? While the HDMI screen works just fine?
Went back to the shop, they tried it out and showed me it worked for them just fine. Hmmm.... Something is weird here. I tried the cable again, ensured everything is firmly connected as it should be and retried. Green screen, AGAIN.
Previously I used the cable that came with the monitor (an single-line DVI-D connector to the DVI-I input). Is it possible that (since the new cable is a dual-line connector) the monitor is underpowered or doesn't accept the translated protocol? Or should I be searching here for problems with the GPU?

[itsmyname]

@Nezerol -- Went back to the shop, they tried it out and showed me it worked for them just fine.

Did you take your computer and your monitors to the shop?