So an overclocked 2500k/2700k + 1080 Ti. Bravo, you're playing it smart, but that will cover max settings at 1080p almost all games, if we aren't talking about 144Hz+ monitors, and we leave mods out of it. In the world of PC gaming there is no truly "maxed" system. Doesn't exist. This thing comes about as close as possible.
It can play nearly any game ever made. There is no more capable OS for emulation than Windows, and its MSI Godlike motherboard has 10 ports in the front + 6 ports in the back to handle 14x unique USB controllers simultaneously for every console from the past (-2 for the Keyboard+Mouse). It has the processing power to eat through the most demanding, accurate emulators.
PC
Windows 10, Supreme 4K/1440p level of gaming currently
Linux/SteamOS, Supreme 4K/1440p level of gaming currently
Windows 8 & earlier, compatibility mode ftw (i.e. just about any PC game made before 2019 is gonna play on this thing that hasn't already been updated to modern operating systems)
Microsoft
Xbox One X [Enhanced Xbox One HDR/4K gaming]
Xbox 360, backwards compatibility (568 titles)
Xbox, backwards compatibility (39 titles)
Sony
PS4 Pro [Enhanced PS4 HDR/4K Gaming]
PS3, PS Now (352 Titles)
PS2, PS Now (12 Titles) & PCSX2 (High Accuracy Emulation)
PS, Medfanen (High Accuracy Emulation)
Nintendo
Switch
Wii,
Dolphin (High Accuracy Emulation)
Gamecube,
Dolphin (High Accuracy Emulation)
SNES,
bsnes (Cycle Accurate Emulation)
NES,
Mesen (Cycle Accurate Emulation)
Sega
Sega Saturn,
Medfanen (High Accuracy Emulation)
Atari
Atari Jaguar,
Phoenix (High Accuracy Emulation)
Atari 7800,
MAME (High Accuracy Emulation)
Atari 5200,
Altirra (Cycle Accurate Emulation)
Atari 2600,
MAME (Cycle Accurate Emulation)
Everything Else
It can run just about everything else from the 90's and earlier (ex. Classic Arcade, Neo-Geo, 3DO) via emulation including many handhelds like the PSP & Gameboy Advance. It can even run Android. It's not the same the ease of plug and play, but the ease of plug and play doesn't itself include the ease of downloading ROMs.
This above list doesn't include any emulators that run at Medium Accuracy or below, have low rates of compatibility, or that aren't native and regularly updated to Windows 10. This chopped of the Wii U, Nintendo 64, Sega Dreamcast, and Sega Genesis from the major players. Out too go handhelds like the 3DS & Vita. But, quite simply, this is the most capable gaming machine ever produced.