A passive DVI to HDMI cable is limited to single-link DVI-D which means a TMDS clock of 165MHz and a maximum resolution of 1920x1200 or 2048x1080 at 60Hz. The fact that they work on the 2K Omen 27i means the cable is most likely fine. The LG 32GR93U-B appears to support a maximum of 3840x2160 at 144Hz. What resolution is the old GPU attempting to drive the display at? Trying setting it to one of the ~2K resolutions.

The problem is from BIOS which seems to display in 800x600, and continues to Windows, when setting resolution up to FullHD changes nothing. Same problem diffrent DVI GPU, new with native HDMI/Displayport works fine, so probably some signal incompatibility.

voodoo1907 wrote on 2025-10-31, 09:09:

Hello I have a problem with connecting old GPU's like FX 5200, HD 3870 to my 4k LG 32gr93u-b - both of these cards use DVI output so I'm using DVI to HDMI cable. Unfortunately my display shows horizontal lines across half of the screen, same with both GPU's. Connecting to my girflrends 2k Omen 27i, everything wors like a charm(I've tried to change scaling, VRR etc notthing works). I don't have space on my desk for second old display, and don't want to change existing one just because of this, so I'm wondering if someone had similar issues, and maybe can recommend some adapter that can deal with such problems. The best will be some active DVI to HDMI but I don't think such exist xD but maybe using DVI->Dsub dummy adapter which I have (both cards have only 2 DVI, but i think they must have analog output in it), and then some good Dsub -> HDMI converter?

Option 1
Change your girlfriend.
Although finding a soulmate who wouldn't mind such a strange hobby will be difficult.
Option 2.
AGP video cards will never be powerful enough for resolutions even close to Full HD. Moreover, applications from that era are very sensitive to aspect ratios other than 3:4.
The best option is to look for a 3:4 monitor with DVI and resolutions from 1024*768 to 1600*1200.
They are still available.

voodoo1907 wrote on 2025-11-01, 07:35:

The problem is from BIOS which seems to display in 800x600, and continues to Windows, when setting resolution up to FullHD changes nothing. Same problem diffrent DVI GPU, new with native HDMI/Displayport works fine, so probably some signal incompatibility.

Please confirm that it is full HD at 60Hz. What are the resolutions and refresh rates offered?

I don't have a 4K monitor, only a 2.5K (2560x1440 60Hz, no VRR) one. I tried connecting an AMD 780G (AM2+) to it using a DVI-HDMI adapter, then an HDMI cable. This is quite close (RS780, GFX3, DCE3 ) to the HD3870 (RV670XT, GFX3, DCE2) i.e. both TeraScale 1.

Boot up is fine (standard Award 6.00PG BIOS with Energy Star logo). Beyond that is Linux, grub bootloader displays fine (text mode), once the Linux kernel starts the screen goes blank saying "No signal", I think it tries to set the native 2560x1440 which is beyond single-link DVI-D. Then the login screen appears (KDE Plasma 6.4 Wayland) and it's in 1920x1200. Once on the desktop, I can manually set 2048x1080 and that's also fine. It does offer 2560x1440 but manually setting that causes the screen to go blank again.

I'm not sure if the motherboard supports dual-link DVI (the manual doesn't say) but it would need that for resolutions beyond ~2k so if it ended up using dual-link then half the pixels are essentially missing since HDMI only supports one link.