I built this PC in 2022, but games such as Marvel Rivals, Fortnite, and Valorant have become completely unplayable. This is more than ordinary lag—the screen can stay stuck on a single frame, and I cannot move or interact with anything. I have tried using Ethernet, updating drivers, changing network and game settings, installing a latency-related utility, and repairing a second monitor, but nothing has helped. My university's internet connection seems reliable, so I do not think ordinary Wi-Fi lag is the cause.
The system has a Ryzen 7 5800X, an RTX 3060, 32GB of DDR4 RAM with XMP enabled, a 500GB WD SN770 NVMe SSD, an unbranded 5TB hard drive, and an EVGA 700 GD power supply. The PC used to run games, although they were sometimes laggy, and the severe freezing is a newer problem. What should I test first to find out whether this is caused by the GPU, drivers, temperatures, storage, memory settings, Windows, or something else?
4 Answers
First confirm that your monitor cable is plugged into the RTX 3060, not the motherboard’s video output. Then monitor CPU and GPU temperatures, clock speeds, and utilization while a game is running. Overheating, a failing cooler, or severe throttling could explain why performance suddenly became much worse. Also check that the SSD is not nearly full, since some drives slow down significantly when they have little free space.
Try a clean graphics-driver installation with Display Driver Uninstaller, then install the current NVIDIA driver. If that does not help, reset the BIOS to a known-good default configuration and leave XMP disabled while testing. Unstable memory settings can cause freezes even when the computer appears to boot normally. You can also reseat the RAM and graphics card to make sure they have good contact.
Use synthetic benchmarks and memory tests instead of relying only on games. Check whether the CPU, GPU, and RAM behave normally under load, and look through Windows Event Viewer for display-driver, hardware, or WHEA errors. Since the PC worked better before, pay particular attention to temperatures, clock speeds, and anything that changed recently, including new software or possible malware.
If the hardware checks out, test with a clean Windows installation as a last resort. Back up important files first, create installation media on a blank USB drive, and reinstall Windows completely. Before restoring extra utilities, test a game with only the chipset and graphics drivers installed so you can determine whether some background program is causing the freezes.

I’ll check whether I’m running a Windows preview build and will test with XMP disabled. I also didn’t realize the display cable could be connected to the wrong output, so I’ll verify that.