That's not an FPS spike. I thought you meant you're playing at 120FPS and it went higher than 120FPS (that's what a spike is), which of course sounded weird since you can't get more than 120FPS if you did everything correctly. Since you're not getting a solid 120FPS, the "low latency vsync" method won't work. This method should only be used if you can maintain the target FPS cap for the majority of the time. You need to constantly hit your cap. If you're not, you're not getting a latency reduction and you get stutter on top of that. In your case, I would recommend using CRU to add a 90Hz mode, and then use this method with a 90FPS cap. Again, same thing: find out the true refresh you're getting, and cap to 0.007 lower. However, since you're introducing a new mode, you can just make sure to make that mode be 90.007Hz then then cap to exactly 90FPS. Make the 90.007Hz mode and then test it on vsynctester to make sure that's what you get. It doesn't have to be exactly 90.007. Anything between 90.006 and 90.012 will work just fine. In-game limiters aren't accurate enough. Some may be, but usually they're not. RTSS is accurate enough. Since this method requires ~0.007FPS accuracy, you really need RTSS. For g-sync, in-game limiters are better since it's not important to be super-accurate, but for vsync, RTSS is better. You can try though. In-game limiters usually only allow whole numbers, so if you change your refresh rate to be anywhere between XX.006Hz to XX.012Hz, then you can set the in-game limiter to XX FPS. But most limiters will produce either slight stutter or add input lag since they can't stay within 0.007FPS accuracy. Yes. With 1/2 vsync, your effective refresh rate becomes half your actual refresh. So you need to cap "as if" you were running 60Hz. However, it's better to just add another refresh rate. 90Hz is much better if you can maintain 90FPS. Prior to getting a g-sync monitor, I had added a couple extra refresh rates just for doing this method: 80.007Hz, 90.007Hz and 100.007Hz. So basically I was trying to "emulate" a very coarse "poor man's g-sync" Are you using 1/2 vsync in inspector? You need that. Note that setting that option might require a reboot. The driver has a bug where the option doesn't apply unless you reboot. You need to check if you're actually using 1/2 vsync. Disable the frame cap (set 0FPS in RTSS). The game should stick to 60FPS. If it climbs higher, then 1/2 vsync is NOT active. But again: 90.007Hz + 90FPS RTSS cap will give you a much better experience.