Why Do PC Games And Emulators Run At Half Speed On 4k T.V.?

[sipes760]

I just bought my first 4k television yesterday, and I am having a strange problem. Whenever I change my desktop resolution to 3840x2160 (my T.V.'s Resolution) all games whether they are PC games or games running on emulators will only run at 30fps. But if I set the desktop resolution back down to 1280x720 everything runs at full speed. Everything else on the PC (like videos and standard programs) run great when the desktop resolution is set to 3840x2160, only games are affected by the resolution change. My question is this, if I am not changing any of the emulators or games graphics settings from what I have always used then why does moving my desktop resolution up affect gaming the way it does? I am only asking for curiosity because it makes no sense to me. I would appreciate any answer anyone can give me on this subject.

[neil9000]

6 minutes ago, sipes760 said:

I just bought my first 4k television yesterday, and I am having a strange problem. Whenever I change my desktop resolution to 3840x2160 (my T.V.'s Resolution) all games whether they are PC games or games running on emulators will only run at 30fps. But if I set the desktop resolution back down to 1280x720 everything runs at full speed. Everything else on the PC (like videos and standard programs) run great when the desktop resolution is set to 3840x2160, only games are affected by the resolution change. My question is this, if I am not changing any of the emulators or games graphics settings from what I have always used then why does moving my desktop resolution up affect gaming the way it does? I am only asking for curiosity because it makes no sense to me. I would appreciate any answer anyone can give me on this subject.

Check in your GPU's control panel that the refresh rate is set to 60, Windows often sets  PC's to 30 when first connecting a 4K display. There could also be other issues, like does your GPU/or integrated GPU motherboard HDMI port actually support 4K as if the physical HDMI port on your PC doesnt support it there is nothing you can do about that short of getting a new motherboard/GPU, and do you have a good quality HDMI cable, as old cheap ones will lack the bandwidth for full 4K60.

[sipes760]

It looks like a gpu issue. I'll just switch resolutions before I play a game It is not that big of a deal it only takes a second. 

[Elhora]

i remember , far far ago, i had some similar problem, and it was because i was using hdmi 1.4 or displayport 1.2 (i don't remember well) that was limiting the 4k resolution to 30i/s.

i switched to DP 1.3 on my monitor (plus a good certified cable, as some cheap chinese cable were causing troubles) and everything was 60i/s...

But if you say you are at 60i/s on your desktop, then that might not be that.

Edited October 14, 2020 by Elhora

[MadCoder]

It's not a GPU, Cheap TV or hardware issue. It's actually pretty simple. The refresh rate of your 4K usually around 29-30Hz, while your emulator and OS are defaulting to higher 60Hz.

You need to ensure GOU Scaling is turned off, and your internal resolution and OS resolution are the same. Example below:

 

[neil9000]

2 minutes ago, MadCoder said:

It's not a GPU, Cheap TV or hardware issue. It's actually pretty simple. The refresh rate of your 4K usually around 29-30Hz, while your emulator and OS are defaulting to higher 60Hz.

You need to ensure GOU Scaling is turned off, and your internal resolution and OS resolution are the same. Example below:

 

It can absolutely be a GPU or cable issue. If the actual device outputting the signal, be it a motherboard when using onboard graphics, or a dedicated GPU only has a HDMI 1,4 output port, you will be limited to 4K30. This is a hardware limit and not something you can just apply in the GPU control panel. As you can see in the below spec page from hdmi.org HDMI 1.4 can only support 3840x2160 at 24, 25 and 30hz. So if the user has a older GPU, which can be quite common in the emulation community as current high end GPU's are not required for most emulation then they simply may be hardware restricted.

https://www.hdmi.org/spec/hdmi1_4b

[MadCoder]

40 minutes ago, neil9000 said:

It can absolutely be a GPU or cable issue. If the actual device outputting the signal, be it a motherboard when using onboard graphics, or a dedicated GPU only has a HDMI 1,4 output port, you will be limited to 4K30. This is a hardware limit and not something you can just apply in the GPU control panel. As you can see in the below spec page from hdmi.org HDMI 1.4 can only support 3840x2160 at 24, 25 and 30hz. So if the user has a older GPU, which can be quite common in the emulation community as current high end GPU's are not required for most emulation then they simply may be hardware restricted.

https://www.hdmi.org/spec/hdmi1_4b

I'm very aware of HDMI's protocols and limitations. However...

Hardware restrictions wasn't mentioned, or even considered seeing that the original post was about a 4K display which assumes the end user must, or should have,  decent hardware installed to get the intended performance. I ship about 5-10 custom builds a week and this is the most common issue I see once it arrives and the customer hooks up their build to a new 4k which will make make the GPU adjust. What's really nuts is when a $4k custom builds maxes out at 12FPS in mame because the customer has a $75,000 99" 16k QLED TV. 

 

[Your Friendly A.I Overlord]

Just to add to the discussion. For 4K60 you need Premium High Speed (18 GB/s) HDMI 2.0 cables. Some HDMI cables are sold with HDMI 2.0 4K on the packaging but only have a bandwith of 10.2 GB/s (4K30). If you connect your pc through a receiver your receiver needs to be compatible and connected with 2 18 GB/s HDMI 2.0 cables.