a few things are odd about your Gainward GeForce GT 640, it being listed in your GPUZ as a GK107 gives me the specs information but a few things dont match, namely (aside your shaders being way low) your memory clock is 667Mhz when the GK107 clock is rated at 891 MHz. Either this is a bad lottery card., a refurbished one at a lower set, of GPUZ is lying to you.
try running speccy (https://www.ccleaner.com/speccy )and then once it is loaded, click on graphics and look at could you copy and paste the details you see there ? curious if the information it finds matches what GPUZ found.
also I would run PassMark Performance test, and see what it reads your video card details as and benchmarking it to see how it rates in numbers versus other GT 640.
https://www.passmark.com/products/pt.htm