I have iMac (21.5-inch, Late 2013) NVIDIA GeForce GT 750M 1024 3.1 GHz Intel Core i7 16 GB 1600 MHz DDR3 . Blender 2.78
When I try to render with the GPU I get the message CUDA error. Out of memory in cuArrayCreate(&handle,&desa)
Render on your i7 it’s very easy to hit a 1024 MB memory limit. And 1024 is actually low enough that I would not even try to optimize anything to fit in that tiny space because it probably won’t be enough either way
Your graphics card has very little vRAM, and the scene should fit on graphics card vRAM. You look in google about some tips to reduce the use of vRAM in the scenes for Cycles.
Also very important, heavy operating systems such as Windows 10 could make much use (or bad use) of vRAM. So use your intel iGPU as the primary display. If you need to use nvidia as the primary display, then use a lightweight operating system like Linux with a lightweight desktop like Xface or LXDE (or LXQT) can help.
If you use Windows, you can see the vRAM usage with programs like GPU-z
Anyway as OriginalSin recommended you, your CPU could be much faster than that card that you have.