HELP! I'm dropping frames for no reason! (xl2540)

[SkyJax]

PLEASE HELP

So back in November I built a new PC and got a nice xl2540 for myself so I could play games in glorious 240hz. After I got everything hooked up and started playing I realized that I was dropping frames in games that locked their FPS to your refresh rate. Geometry Dash is the game that I notice this in most. I play the game a lot and I'm also very familiar with playing at 144hz, and although I could see a difference in the smoothness of the game, I was still getting random drops to 235 or 236 which make the game impossible at high level play (Just for reference, the FPS can not be unlocked in Geometry Dash without an exploit, and even then the game is very choppy due to it not being optimized for FPS higher than 240). I don't notice drops at all in any other games I've tested. That includes Fortnite, CSGO, Osu, Arma 3, GTA V and Rainbow 6 Siege.

I initially thought it was a problem with my PC. I had a Ryzen 7 2700x and an RTX 2070 in that rig so things should have been fine. But I decided anyway to build an entirely new PC which I finished recently. The new rig has an i7-9700k and an RTX 2080ti which I'm aware is totally overkill for a game like Geometry Dash, but I digress. In short, the game still lagged and dropped FPS despite having 8 cores and 11gb of v-ram so I switched my suspicions to the monitor.

As I've already mentioned, it's a BenQ xl2540 and I love it to pieces. It has loads of features and is super high build quality, worth every penny. But since I have very limited knowledge of monitors I thought that maybe the monitor itself could be the problem. The only way to test this would be to use the monitor on another PC, which is exactly what I did today. I set it up at a friends house on his PC (i7-8700k, GTX 1080) and the game seemed to run fine with literally no drops in FPS. This upset me a lot since I've been researching what the problem could be for the last 5 months to no avail, and Blur Busters may be my last hope.

If you guys could tell me what's causing these inconsistencies in FPS or whether it's my monitor or my PC, I'd be super grateful. I'm on the verge of ordering an AW2518HF to see if it fixes my issues, but I doubt that it will. If anyone has a question or wants to suggest a fix, please please do, every little helps.

Thanks, and have a great day!

[Chief Blur Buster]

Before we proceed, we need to verify whether frame skipping is caused by the monitor or not.

Please test www.testufo.com/frameskipping

Take a long camera exposure, 1/4 second to capture about 60 squares out of 240. (Dim the screen if necessary, or use a manual-settings camera app such as ProCam for iPhone). The reason I do this is some monitors skip only 1 out of 40 refresh cycles due to a firmware bug.

The XL2546 is not known to be a frameskipping monitor, so we need to verify first.

One common fix for monitor-side frame skipping is a minor tweak via Custom Resolution. But, first, we have to verify monitor fault or computer fault.

Appreciated!