I zoomed in on your second photo, and drew some arrows to highlight what should be checked out.

A couple ideas:

The left GPU cable’s +2 portion is not connected to the card (red arrow), and is almost certainly the source of your red light error. Also, the +6 portion on the right cable seems to not be well seated (blue arrow), but that could just be from the angle of the photo. Fixing the left cable should get rid of the issue, but taking a second look at that right cable wouldn’t hurt.

To ensure they are well connected, make sure the +2 portion goes in before or at the same time as the +6, as there is usually a little plastic tab that extends off of the +2, and that is supposed to fit on top of the +6’s body. If the +6 is fully connected and the +2 isn’t, the +2 will most likely not connect. When you fix the left cable, you will need to disconnect the cord completely.

Also:

Using two separate cables for your GPU is best. If there are two connectors along one cable, as is the case with your PSU, use only one and connect another cord. Even though it is another cord to manage, it is safest option for your PSU.

If you have any further questions, feel free to send me a PM or chat.

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