Is there any way to add a frame limiter to this game without using Kentie's mod?

Problems with the frame rate being too high generally occur on multi-core setups, which Deus Ex does not play well with. Use the Task Manager to set DeusEx.exe to use only one core. (From the Processes tab, with Deus Ex running, right-click DeusEx.exe and select "Set Affinity...")

what boct1584 said plus, try maybe turning Vsync on?

Tried Vsync and changing affinity, neither worked.

Hmm, maybe post your PC specs

Windows 7 64-bit
i7-2600k 3.40GHz
2 GTX-480's in SLI (I've tried the game with SLI and without)
8-GIG ram

Updated to the lastest card drivers, and all.

Try adding FrameRateLimit=100 or 60 in DeusEx.ini into the renderer section you're using D3D/OpenGL

Downloading the DirectX 10 renderer seems to have fixed my issue. Thanks for all the help.