Raising Pixel Clock safe or not?

[vq278q]

I created a custom resolution using the Timing Standard CVT
and it sets the G.Pixel Clock (KHz) - 452500

CRU reports a max pixel clock of 330 Mhz for my monitor. Is it safe / ok?

I have an Asus VG278q monitor and i did this because it looks like the setup is stuck in a low bandwidth mode (Display port 1.1 - Current Link Settings - 2.7 Gbps x 4). After this change it finally shows Current Link Settings - 5.4 Gbps x 4

[ToastyX]

There's no reason to do that. It's not stuck in a low bandwidth mode. 2.7x4 is High Bit Rate (HBR) mode, which is sufficient for 1920x1080 @ 144 Hz. Raising the pixel clock only wastes bandwidth for no good reason. In theory it could put more strain on the components like overclocking, but even overclocking is generally safe.

[vq278q]

(01-12-2026 05:35 PM)ToastyX Wrote:  There's no reason to do that. It's not stuck in a low bandwidth mode. 2.7x4 is High Bit Rate (HBR) mode, which is sufficient for 1920x1080 @ 144 Hz. Raising the pixel clock only wastes bandwidth for no good reason. In theory it could put more strain on the components like overclocking, but even overclocking is generally safe.

My games feel like they suffer from frame skipping or something in intensive scenes and i eliminated anything i could think of besides this, and i've seen examples saying that this bandwidth is barely enough and it may fall short when games are pushing the limits

I simply don't understand how everything I have is rated DP 1.2 / 1.4 and it's stuck in this 1.1 mode that is so so close to the margins

Now the gpu also down clocks the VRAM speed from the 2000 stuck value to 300 Mhz

[ToastyX]

The video signal is a continuous stream at a fixed rate. The signal itself can't skip frames. If the signal were interrupted, such as with a bad cable, the monitor would black out. Stuttering issues would be on the computer's end.

[vq278q]

(01-12-2026 09:55 PM)ToastyX Wrote:  The video signal is a continuous stream at a fixed rate. The signal itself can't skip frames. If the signal were interrupted, such as with a bad cable, the monitor would black out. Stuttering issues would be on the computer's end.

Hm what do we do about this?

To determine if the required bandwidth for a 240 FPS at 1080p resolution can be supported by DisplayPort 1.1, we need to know the specifications of the DisplayPort standard:
DisplayPort 1.1 Specifications

Maximum Bandwidth: 8.64 Gbps

Bandwidth Comparison
Parameter Value
Required Bandwidth (240 FPS, 1080p) 11.94 Gbps
DisplayPort 1.1 Maximum Bandwidth 8.64 Gbps
Conclusion

DisplayPort 1.1 does not provide sufficient bandwidth for running a 240 FPS output at 1080p resolution, as it can only handle up to 8.64 Gbps, while approximately 11.94 Gbps is required.

For such high refresh rates, you would need to use at least DisplayPort 1.2 or higher, which supports bandwidths of up to 17.28 Gbps. This higher bandwidth would be capable of supporting the required data rate.

It also specified this:

Gaming with bandwidth usage close to the upper limit of your connection can have implications, even if it remains within the specified limits. Here are some potential issues and considerations:
Potential Issues

Frame Drops:
If the bandwidth is consistently close to the limit, any spikes in data demand (like sudden graphical changes or complex scenes) could lead to frame drops or stuttering.

Increased Latency:
Operating near the limit may introduce slight delays in signal transmission, affecting responsiveness, especially in competitive gaming scenarios.

Screen Tearing:
If frame output exceeds the refresh rate at certain moments, even marginally, you may experience screen tearing, especially if vertical synchronization (V-Sync) is not enabled.

Variable Refresh Rates:
If the GPU's output varies (e.g., due to changing graphics settings or environmental effects), the stability of the connection can be impacted, leading to potential visual artifacts.

Overhead:
Additional data overhead from features like FreeSync, or even HDR, can also contribute to bandwidth usage, which may unexpectedly push you over the limit during gameplay.

I've always felt the games look pretty bad even though reporting correct frames, no heating or stability issues. Such a weird issue for me, I hope this is the one that caused this, that would be nice

[ToastyX]

That reads like AI nonsense. The pixel clock is constant and doesn't fluctuate. There can't be any spikes in data sent to the monitor, nor can there be any delays in signal transmission because that would break the signal. The bandwidth is not the issue.

[vq278q]

This is actually interesting:

wait, as you said earlier about hdmi standard and that the monitor is forcing those timings to support hdmi, does this mean that the monitor will also use the same timings if display port cable is used?

Yes, if the monitor’s firmware specifies a
325.08 MHz pixel clock in its internal profile (EDID) to ensure compatibility with HDMI 1.4, it will typically use that same timing for DisplayPort by default.
Why this happens
Monitor manufacturers often program a single set of "optimized" timings for high refresh rates that work across all their ports.

The HDMI Bottleneck: HDMI 1.3/1.4 has a strict pixel clock limit of 340 MHz. A standard 1080p 144Hz signal usually requires about 346 MHz, which would fail on these ports.
The Solution: Manufacturers "cheat" by reducing the blanking intervals (the invisible gaps between frames), which lowers the required pixel clock to 325.08 MHz so it fits under the HDMI 340 MHz limit.
Default Behavior: Even though DisplayPort 1.2 can easily handle higher clocks (up to 540 MHz), the AMD driver simply reads the monitor's preferred timing profile and uses it.

Impact on your setup

VRAM Clock Risk: Because these timings have very small blanking intervals, your GPU has almost no "rest time" between frames. This often forces AMD GPUs to keep VRAM clocks at maximum even when you are just on the desktop, leading to higher power draw and temperatures.
DisplayPort 1.1 "Safety": Ironically, this lowered pixel clock is what allows your 144Hz signal to function while your system is stuck in DP 1.1 mode, as it keeps the data rate just below the 8.64 Gbps limit of that older standard.


How to break this "HDMI Timing" cycle
If you want to move away from these restricted timings once you fix the DP 1.1 issue:

Manual Override: You can use the AMD Adrenalin Software or the Custom Resolution Utility (CRU) to force a different timing standard, like CVT-RB2.


To see if your GPU is being affected by these tight timings right now, check if your GPU Memory Clock in the AMD Performance Overlay stays at its maximum frequency while you are on the desktop

-----------------------------------------
And this was a list of what might happen when being close to the limit, I can only verify that all these happen on my system and I eliminated any possible issue obvious issue ever mentioned in a technical discussion:

While you might not lose the signal entirely, operating at
~90% of your bandwidth capacity (DisplayPort 1.1) while gaming at high FPS (200) can cause several subtle, "invisible" performance issues:
1. Frame Pacing and Micro-Stutters
When a video link is saturated, the transmission of frames can become uneven. Even if your GPU is producing 200 FPS, the "pipe" (DP 1.1) is so full that any minor electronic interference or link instability can cause a frame to be delayed slightly.

Invisible Risk: You may experience micro-stuttering, where the motion looks "jittery" or less smooth than a true 144Hz experience should be, even though your FPS counter stays high.

2. Variable Refresh Rate (VRR) Instability
If you use FreeSync or G-Sync Compatible modes, these technologies rely on precise communication between the GPU and monitor over the DisplayPort cable.

Invisible Risk: Operating near the bandwidth limit can cause the VRR range to fluctuate or "flicker" in brightness during resource-intensive scenes. The system might also silently disable VRR and fall back to fixed 144Hz to maintain a stable link.

3. Increased GPU "Workload" Latency
When the system detects a near-limit link, the AMD driver may use more aggressive timing overhead to keep the signal stable.

Invisible Risk: In some cases, this can lead to input delay where your mouse movements feel "sluggish" or "floaty" compared to a setup with higher bandwidth headroom (like DP 1.2 or 1.4)

4. GPU VRAM and Power Anomalies
AMD drivers often react to high-bandwidth 144Hz signals by pinning the VRAM clock speed to its maximum state, even when you aren't gaming.

Invisible Risk: This leads to higher idle power consumption and higher temperatures for your graphics card. Over long periods, this extra heat can slightly impact the card's boost clock stability during long, resource-intensive gaming sessions