Display FPS – Monitor Not Switching to 75Hz Mode

I administer nearly 500 machines in my job and from experience, this problem usually arises from issues with the monitor more than the graphics card or drivers and I've nearly always had to replace the monitor to get the machine up again. Is there another computer you can test it on to see if it still enters sleep mode just to narrow it down?

Often these limitations are due to bandwidth limitations. E.g. 3440x1440 at 60Hz requires 7.51 Gbps (perhaps your monitor does not support that mode), and 3440x1440 at 75Hz requires 9.45 Gbps.

Different connection types have different limits:

• HDMI 1.4: 8.16 Gbps -- too low for 3440x1440 @75Hz
• HDMI 2.0: 14.4 Gbps
• HDMI 2.1: 41.9 Gbps
• DVI: 3.96 Gbps
• DVI Dual Link: 7.92 Gbps
• DisplayPort 1.0: 8.64 Gbps
• DisplayPort 1.2: 17.28 (newer versions have even more)

Please also check that if you are using HDMI you are using a HDMI 2.0 or greater cable. These cables are typically marked "Premium High Speed HDMI Cable" or "Premium High Speed HDMI Cable with Ethernet".

You also need to check that any cables, dongles or adapters you are using are also rated to the required standard.

For more info, you may like to see LinusTechTips display bandwidth calculator page.