Do new 4k gaming monitors hook up to old receivers? (currently hooked up to hdtv) Thanks!

you can use old receivers for sound, I do it with a 4K TV and 1080P capable receiver, but you have to run two cables. Basically you run one cable directly to your TV for video and another to your receiver for audio. I tried originally using both an optical connection and hdmi arc (audio return channel) but had issues with 5.1 and 3D sound not working properly in all software/games/apps. So what I had to do was this. I run one hdmi 2.0 cable to my TV for video then using my DVI port on my GPU i run a DVI to hdmi cable to my receiver. Windows see's the receiver as a monitor and can therefore receive sound from the GPU solving 5.1/3D sound issues optical and hdmi arc can have. This does however cause there to be a phantom monitor in the upper right side of my screen (ie the mouse will keep going to the right like a screen is there). Point being it can be easy to temporarily lose your mouse so keep that in mind. Ideally you want to run a receiver that is 4k capable with hdr and 4:4:4 sub-sampling at 60hz but money doesn't grow on trees so hacks like mine work to get us by.

edit: in your case hdmi won't be present so you'll be forced to use optical audio or av to headphone jack converters from your motherboard/sound card.

happy to help. I have been wanting to replace mine as I run several HDMI device through it and I recently got 4K. As of now my PC and PS4 bypassing it for (4k/hdr for PC and hdr for PS4) and do as stated above to bypass for PC...for PS4 I use the HDMI ARC channel. Point being soon I'll have more 4K/HDR capable devices and will need the receivers multi HDMI input to keep up.