I have i5-10400 without GPU. I am using an 8 GB ram stick. So, if igpu use 50% I have some issue to run the pc smoothly. I need to decrease the shared ram from 4 GB to 2 GB. Is there any way to do that?
Motherboard- Asus Tuf B460 Gaming Plus
No you don't. The driver starts with only a minimal allotment of memory. As needs dictate, this may increase up to 50% of available memory - but this is only while needs dictate; once needs drop, the allotment will drop as well.
There are some games that see the maximum allowed and immediately allocate all of it and fill it with textures, etc. to supposedly speed things up. This is wrong. There is nothing that you can do about games that do that (well, other than give the developers heck, which you should).
Not necessarily. Most BIOS, when they see that an add-in graphics card (dGFX solution) is present, will automatically disable the iGFX solution. Some don't. Some leave iGFX enabled in case it is needed to support certain capabilities (transcoding, DRM, etc.) that dGFX doesn't/can't support or just to support additional monitors being connected via the mobo. If it is being left enabled but is not used, the resources consumed are minimal. Still, if you want it disabled so even the base allocation is not consumed, you can usually do so within your mobo's BIOS Setup facility. There is usually an Enable iGFX parameter that supports settings like Auto (enable if no dGFX, disable if dGFX), On/Enable (always enable) or Off/Disable (always disable).