Question Artifacts JUST on setup screen

[no--name]

So I needed to build a 3rd system for my workshop and bought this old Q9400 on the Internet, I knew it have had some issues because the seller told me the on board ethernet wasn't working, probably it had an over voltage peak from a lightning or something. He said everything else was working properly and as it was very cheap I bought it.

I just received it today, the first thing I tried to do is to access the setup and check basic settings and noticed it only renders the 15/20% of the screen starting from the top, the rest is artifacts and pitch black. I can see the first two options and it seems I can enter them normally, I'm just unable to see what I'm doing there.
My thoughts were that what killed the ethernet damaged also the GPU, however I booted the system into W10 and everything seems to work fine, no artifacts at all, the POST screen doesn't show anything bad either, problem seems to be just when you enter the setup.

Tried cleaning the CMOS and it didn't help, I would like to try with a dedicated VGA but I don't have any on hand.
I could eventually try a BIOS upgrade but sounds risky given the circumstances.

Anyway, I have 30 days where I can refund my money at any time, however I would like to keep it as this CPU is amazing for the price I paid. Can you guys think on anything else I can try to fix this issue?

Edit: SS

 

[AJNameS]

When I sold an ultra-cheap GPU to a guy who had the same problem, everything got fine. He used the mobo for display before, but it sucked. It worked just with a fine PCIe x16 low-end one.
If trying a bios update, at first see what your current version is. I usually can find latest bios updates for socket 775 mobos, but it may not change anything.