Does your 4K 60 Hz monitor only work at 30 Hz? Why it happens and how to fix it

A few days ago, when I changed my monitor, I ran into a pretty absurd problem.

Both the old and the new one were 4K@60Hz monitors, except the new one is portable (I want to be able to carry it around easily) and only has miniHDMI or USB-C video input.

And of course, the graphics card I use in my desktop is a professional Nvidia Quadro P620 that only has four mini DisplayPort outputs, at 4k@60Hz, mind you

Obviously I don't have a miniDP to miniHDMI or USB-C cable, because that's a pretty unusual combination. So I did the obvious thing: tried the different adapters I had around the house, and I have quite a few.

After trying several combinations (I'll tell you about them below), the result when everything was connected was 4K at 30 Hz.

A ridiculous refresh rate to work at. If you've never used it, try setting your system to those 30 Hz and you'll see what I mean.

I fixed it. Without buying anything, too. I'll tell you how in a moment, but first it's worth understanding why you can run into this problem even when, apparently, all your hardware supports 4K@60Hz.

Your monitor and PC supporting 4K@60Hz does not mean you will get 4K@60Hz. Considerations

That was exactly my initial mistake.

I assumed that if the monitor supports 4K@60Hz and the graphics card does too, the logical thing would be to connect them and be done with it. And that would be true if we could connect both devices directly using a compatible connection, namely the miniDP to miniHDMI or USB-C cable I mentioned earlier.

But if you don't have one, the problem appears when you put cables and adapters between them:

Graphics card > adapter > converter > cable > another adapter > monitor.

In my specific case, the initial chain ended up being:

Graphics card > miniDP to DP adapter > DP to HDMI adapter > HDMI cable > HDMI to miniHDMI adapter > monitor.

Almost nothing.

Especially considering that each of those elements not only has to be able to carry a 4K@60Hz signal (in my case they all could), but nothing can be lost across the chain as a whole, which is exactly what was happening.

And that's important, because what we're really talking about here is bandwidth, just like when we used to talk about ADSL, and 4K at 24 Hz, 30 Hz, 50 Hz or 60 Hz does not require the same bandwidth.  

Nor is it the same to transmit the image at 8 or 10 bits of color depth, with or without HDR, or using RGB, YCbCr 4:4:4 or some form of chroma subsampling.

Each of these concepts uses more or less bandwidth and is the key to getting the resolution you want, as we'll see later.

For now, I just want you to keep the general idea in mind and know that the first requirement for getting 4K@60Hz is that the video source can generate that signal.

Your PC output may (or may not) be able to output 4K@60Hz

It has nothing to do with the graphics card being very powerful, although if it's very powerful it probably can. Nor whether it's integrated or dedicated.

The connection matters more, because DVI, DP, HDMI 1.4 and HDMI 2.0 are not the same.

DVI does not support 4k@60Hz.

DisplayPort 1.2, which has been around for quite a few years, could already carry 4K at 60 Hz with 4:4:4 color. VESA specifically lists 4K@60Hz as one of the capabilities of DP 1.2 using HBR2. In my case, all four mini DisplayPort outputs are 1.4, so there's no problem.

With HDMI, things are a little more complicated.

Do you absolutely need HDMI 2.0 to get 4K@60Hz?

Short answer: no, but it is recommended.

The long answer is that it is recommended if you want 4K@60Hz with full color quality, but it is not strictly true that getting 4K@60Hz over HDMI 1.4 is physically impossible.

The HDMI 1.4 specification itself supports 3840×2160 at 24, 25 and 30 Hz, but not at 60 Hz.

However, NVIDIA found a rather curious way years ago to partially work around that limitation.

In 2014, it enabled some Kepler cards and its R340 drivers to send 4K@60Hz over HDMI 1.4 using YCbCr 4:2:0. Instead of transmitting all the color information for every pixel, it reduced its resolution and managed to fit the signal within the available bandwidth.

It worked, although there was a catch.

For video it could be a perfectly reasonable solution, since much audiovisual content already uses chroma subsampling. And for games, something similar (although nobody was gaming at 4K back then).

The problem appeared mainly when working on the PC, because text and certain interface elements lost sharpness.

In fact, I tested it with my ancient GTX-650, with HDMI 1.4, and it output 4k@60Hz without a problem… as long as you weren't using a huge Excel spreadsheet. That's where the trick started to show its seams.

What matters to us is not bringing that solution back, but understanding something:

4K@60Hz is not a single signal.

You can transmit the same resolution and the same 60 frames per second using different amounts of information.

And that will be fundamental to solving our problem.

The real difference between 4K@60Hz and 4K@30Hz

3840×2160 is approximately 8,3 million pixels.

If you refresh those pixels 30 times per second, you have about 249 million active pixels per second. If you do it 60 times, that's practically 498 million.

And that's without counting the additional intervals that are part of the video signal or other transmission factors.

That's why a connection can work perfectly at 4K@30Hz and give you a black screen when you select 4K@60Hz.

It may even work at 40, 45 or 50 Hz and fail beyond that. In fact, I can already tell you that this is exactly what happened in my case.

Cables are not binary

Another important point is that we tend to think about a cable in a very simple way:

It either works or it doesn't.

But when we are close to the limit of a high-speed connection, things can be much more complicated.

A certain combination of cables, connectors and adapters may have enough headroom to carry 4K@30Hz but not 4K@60Hz. 

Or it may work perfectly at 4K@50Hz and stop displaying an image when you ask for those ten extra frames.

Length, cable quality, connectors, interference and the electronics in converters can all affect signal integrity.

That's why an adapter labeled “4K@60Hz” does not guarantee that your specific combination will work at 4K@60Hz once you combine it with other components.

Adapters make things even more complicated

If you connect DisplayPort to DisplayPort, the signal does not have to be converted to another protocol, but when you do DisplayPort > HDMI things change.

Depending on the output and the adapter, a dual-mode DisplayPort output (DP++) may be used, or an active conversion between the two protocols may take place. And the result varies.

You can make it even more complicated. For example:

miniDP > DP > HDMI > miniHDMI

Each hop adds a connector and, in some cases, more intermediate electronics. They can all work correctly on their own and yet the final combination can be more sensitive at high refresh rates.

But wait, there's another factor.

Communication between the GPU and monitor includes more than just the image

In addition to everything we've seen, the information the monitor sends to the graphics card also comes into play, mainly through EDID, where it reports the resolutions, refresh rates and modes it supports.  

Ideally, this communication would always be transferred directly and correctly, but the cables and adapters between the two can cause certain capabilities not to be offered properly.

Right, so with all that, what do we do?

The easiest route would be to buy a direct cable between the GPU and monitor, certified for 4k@60Hz, and save ourselves the trouble.

But if we don't want to spend money unnecessarily, there are other things to try first.

How to fix a 4K@60Hz connection that is stuck at 30 Hz

The idea is to try different solutions before buying anything.

I'm going to order the checks from the simplest to the most complicated. That way you can use these steps as a complete procedure and stop as soon as you find a setup you're happy with.

Step 1. Check the resolution and refresh rate you are actually using

In Windows 11, go to:

Settings > System > Display > Advanced display

Select the monitor (if you have more than one) and check two things:

• Active resolution: 3840×2160.
• Refresh rate: 30, 50, 59,94, 60 Hz or whichever one you are using.

Do not assume you are at 60 Hz just because you selected a 4K resolution. 

Step 2. Check what the video source can actually output

Look up the specifications of your graphics card or integrated graphics and, above all, of the output you are using.

GPUs usually have several types of connection, and they do not necessarily all have the same capabilities.

If you use DisplayPort, check its version and maximum resolution. If you use HDMI, do the same.

And remember what I explained earlier: an output being HDMI 1.4 does not automatically mean it can never generate 4K@60Hz, because modes such as 4:2:0 reduce bandwidth.

Step 3. Also check the monitor resolution and input

Assuming your monitor supports 4k@60Hz, you need to check exactly the same thing we just did, but at the other end.

Some monitors have several inputs, and they do not all offer the same capabilities.

For example, you may have:

• HDMI.
• DisplayPort.
• USB-C with DisplayPort Alt Mode.
• VGA
• DVI

Step 4. Check the cable and adapters

The first thing is to check that your cable supports 4k@60Hz and is not limited to 1080p or 4k@30Hz.

This, which sounds almost painfully obvious, is what happened when the PlayStation 3 and X-Box 360 launched twenty years ago: even if you bought the console and had a monitor capable of FullHD (1080p), if the HDMI cable you connected was 1.2 (many were at the time), you were limited to 720p.

In this respect, if you can use DisplayPort from end to end, it is usually preferable to keep the same protocol rather than convert it to HDMI.

Step 5. Remove as many adapters as you can

This is probably the simplest recommendation in the entire article.

If you are doing miniDP > DP > HDMI > miniHDMI and you can turn it into miniDP > HDMI > miniHDMI ,even better.

And if you can get to DisplayPort > DisplayPort, better still.

The same applies to USB-C: a monitor with USB-C video input may actually be receiving a DisplayPort signal through DisplayPort Alt Mode. If your PC already has DisplayPort, a suitable DP > USB-C cable can avoid the HDMI conversion altogether.

But be careful here because many USB-C > DisplayPort cables are unidirectional. That means they only send video in one direction, generally from USB-C to DisplayPort (or to HDMI, as the case may be)

If you want to connect a DisplayPort output to a USB-C monitor, you need one that explicitly states that direction or is bidirectional.

In short, the fewer connectors, conversions and devices there are between the graphics card and the monitor, the fewer points you have to investigate if something goes wrong.

Step 6. Test the components separately

If you have another monitor, another computer or several cables at home, try changing only one thing at a time.

For example:

• Same monitor and graphics card > different cable. Same type (two different HDMI cables) or different type (swap HDMI for DP).
• Same graphics card and cable combination > different monitor.
• Same cable > different adapter.

Why only one thing?

Because if you change three components at once and it works, you'll know you've fixed it, but you'll have no idea which one caused the problem.

And if it happens again -which is likely if you enjoy tinkering as much as I do-, you'll be practically back where you started.

Step 7. If you convert DisplayPort to HDMI, try an active converter

If you need to keep a DisplayPort > HDMI connection and your current adapter is giving you trouble, it is worth checking what type it is and what specifications it really offers.

An active adapter includes electronics that convert the DisplayPort signal to HDMI instead of relying exclusively on the output itself to generate a compatible HDMI signal.

This can be especially useful when you are aiming for 4K@60Hz, although buying an active adapter does not guarantee that every combination will work either. So if you do not already have one, do not buy anything yet and leave this solution until after trying the next two.

Step 8. Temporarily reduce what you are sending

Before giving up on 60 Hz, you can check whether the problem is really bandwidth-related.

Try, if your graphics card and monitor offer these options:

• Disable HDR.
• Use 8 bits instead of 10 bits.
• Check the available RGB and YCbCr formats.
• Try a lower-bandwidth color mode where available.

As I said earlier, I do not necessarily recommend leaving the desktop using 4:2:0 subsampling because it can noticeably hurt text definition, but as a test it is very useful. Especially if the monitor starts working at 60 Hz when you reduce the amount of information being transmitted.

Step 9. If 60 Hz does not work, try 50 or 45 Hz

And now we reach the solution I find most interesting.

Because there is a middle ground between 4K@60Hz and resigning yourself to 4K@30Hz.

You can keep the 3840×2160 pixels and reduce only the refresh rate.

Going from 60 to 50 Hz reduces the number of images transmitted per second by approximately 16,7 % . Dropping to 45 Hz means a reduction of 25 %.

On a desktop, moreover, the difference between 30 and 50 Hz is much more obvious than between 50 and 60.

So if your connection -for whatever reason- is simply close to its limit, you may find something quite interesting: 4K@50Hz works perfectly while 4K@60Hz gives you a black screen

And you can keep that resolution going forward (it is perfectly workable), avoiding buying absolutely anything.

How to create a custom 4K@50Hz resolution with NVIDIA

NVIDIA lets you create display modes that the monitor does not initially offer from its Control Panel.  

It also offers the CVT Reduced Blanking, which reduces the signal's blanking intervals and therefore the pixel clock required.

The process is this:

1. Open the NVIDIA Control Panel. You can do this by right-clicking the desktop or searching for it in Windows.
2. Go to Display > Change resolution. Select the monitor on which you are having the problem.
3. Click Customize. From that window you can access resolutions that do not appear among the usual options.
4. Click Create Custom Resolution. Keep the horizontal resolution at 3840 pixels and the vertical resolution at 2160.
5. Change the refresh rate to 50 Hz. Keep the scan type set to progressive.
6. Select CVT Reduced Blanking or CVT-RB under Timing. This mode reduces part of the additional intervals used between images and makes it possible to achieve a pixel clock lower than with conventional CVT timing. You do not need to manually change the advanced synchronization values unless you know exactly what you are doing. For this purpose, letting CVT-RB calculate the timings is much easier.
7. Click Test. The screen may go black for a few seconds while NVIDIA checks the new mode. If the image comes back and everything looks correct, save the resolution. If no image appears, do not confirm the change and wait for the previous configuration to return.
8. If 50 Hz does not work, repeat the test at a lower refresh rate. I would start with 45 or 40 Hz. If one of them works, you can then increase it little by little until you find the real limit of your connection.

Based on what you get, you'll see whether you're satisfied or not. In case it helps, here's what happened in my case after doing it this way:

• 4k@50Hz > Black screen.
• 4k@42Hz > Usable, although with a noticeable effect (you could feel the missing Hz while working).
• 4k@44Hz > Unusable, the image flickered.
• 4k@50Hz WITH ANOTHER HDMI CABLE > Completely usable and with no noticeable difference compared with 60Hz. I was happy with this.

What if you have an AMD graphics card?

AMD has practically the same concept within AMD Software: Adrenalin Edition.

The option is called Custom Resolutions. You can create a new profile, enter the desired resolution and refresh rate, and have the software itself check whether the monitor accepts that mode. AMD still provides this function and officially documents the procedure.  

So if you have AMD, the idea is exactly the same:

3840×2160 > 50 Hz > test.

And reduce the refresh rate if it does not work.

What about an Intel graphics card?

Here it is currently a bit more awkward.

Intel says that the current version of Intel Graphics Command Center uses the resolutions provided by Windows and no longer offers the creation of custom resolutions.  

I couldn't get it to work with my system's integrated graphics either (I tested it by disabling the Nvidia card).

As an alternative, Intel recommends installing Intel Graphics Command Center Beta, where, according to Intel's documentation, there is a button to add them, although I have not confirmed it myself.

So the solution is not exclusive to NVIDIA, although it is more straightforward with NVIDIA and AMD.

Step 10. Check that everything is actually working at the new refresh rate

Seeing an image does not finish the process.

Go back to:

Settings > System > Display > Advanced display

and check that Windows shows 3840×2160 at 50 Hz or whatever refresh rate you created.

Then you can use a motion test such as TestUFO and check that the browser is syncing at approximately the refresh rate you selected.

If Windows, the driver and a refresh-rate test all agree, you can consider the configuration good.

Conclusions

The main takeaway is not that you should set your monitor to 50 Hz. No, that's not it.

The important thing is to understand that you should not treat 30 and 60 Hz as the only two possibilities.

If a black screen appears right when you increase the refresh rate, there may be a completely stable middle point. Sometimes it will be 50 Hz, sometimes 45 and, as I found with one of my combinations, there may be a boundary as specific as 43/44 Hz.

Of course, the ideal solution is still this:

Compatible GPU > direct cable connection > compatible monitor.

If you can eliminate adapters or use the right cable and get 60 Hz, do it.

But if you already have a setup working at 4K@30Hz and reaching 60 means buying cables or adapters without even knowing which one will solve the problem, I would try a custom resolution first.

It is step 9 and will take you five minutes.

Along the way, you may end up like me and learn much more about resolutions, color, cable technology and adapters.