The PC is restarting in the middle of gaming?
The motherboard has rev. 1.0/1.1/1.2/1.3 printed on the board? Not rev. 1.4/1.5/1.7? I ask because there's a lot of board revisions for Gigabyte B550M DS3H.
48GB RAM is a non-standard memory configuration.
• When enabling Dual Channel mode with two or four memory modules, it is recommended that using the same capacity, brand, speed, andchips of memory modules and also installed in the same color of DDR4 slots.
https://download.gigabyte.com/FileList/Memory/mb_memory_am4_4L4D_vermeer.pdf?v=390bb5e1cba06dbd4601a1444a6ddffd
The motherboard's Qualified Vendors List states the above quote at the very bottom on the last page of the QVL. The QVL also lists which RAM modules support up to 4 modules and which only support 2 modules.
You can find the QVL for supported memory on Gigabyte's website under Support List. You have a Vermeer CPU. If you have questions about the list let me know and I'll answer.
https://www.gigabyte.com/Motherboard/B550M-DS3H-rev-10-11-12-13/support#support-dl
You can try installing only 2 memory modules that are exactly the same capacity, brand, and speed into DIMM slots A2 and B2 as recommended in the motherboard's user manual. (See attached picture at the end of this post)
Some other things to check are motherboard VRM (Voltage Regulator Module) and CPU temperatures. They should be under 100°C, preferably under 90°C. I recommend HWiNFO for temperature monitoring.
https://www.hwinfo.com/
If you continue to have issues there's also memory test software to check for memory errors. I've personally used HCI MemTest and had good results finding memory errors on my system. The free version isn't very user friendly. I recommend reading the MemTest user manual. Basically you launch a bunch of MemTest windows to speed up testing by using more CPU power. Be careful not to test more gigabytes of RAM than your system has because MemTest will start testing the Windows Page File on the hard drive!
https://hcidesign.com/memtest/