I have 4200 integrated graphic card on motherboard, should I uninstall from device manager or go to bios. On the device mgr. it shows that both are running & it is using 2 mb of ram. The discrete card is a rx460 2gb of vram. Running windows 10 1903.
very little computer setup information to go on.
If the "4200 Integrated Graphics" is a Intel APU then no you don't need to uninstall it since it won't affect the AMD Driver installation. But you do need to have the latest Intel APU integrated Graphics and Chip set drivers installed for the AMD driver to work best either from Intel directly or your Motherboard Support download site.
If your motherboard has both a AMD APU integrated graphics and a AMD GPU card then you need to see if your APU Driver will also support the AMD GPU Card under the AMD Driver's "Release Notes". If it does then you need to uninstall the AMD Driver with DDU in Safe mode with the internet disconnected. Then install the AMD APU Driver which will also install the AMD GPU card driver at the same time.
If the AMD APU integrated Graphics is not supported by AMD with driver updates but the AMD GPU card is then you may have a problem installing the AMD GPU Card graphics. Then someone else will need to help you.
I understand now that your Motherboard has built in integrated graphics HD 4200. It is a very old Motherboard.
This is the last AMD Driver download for your Intergrated Motherboard Graphics from AMD Download page: https://www.amd.com/en/support/graphics/integrated-motherboard-graphics/ati-radeon-integrated-hd-ser...
But MSI Support has it own newer Integrated graphics HD 4200 but for Windows 7 x64 included with its Windows 7 Chipset: Support For 785GM-E51 | Motherboard - The world leader in motherboard design | MSI Global
This is the latest AMD Driver for Windows 10 from AMD Download page: https://www.amd.com/en/support/graphics/radeon-400-series/radeon-rx-400-series/radeon-rx-460
The problem you have is that you have an Unsupported Integrated graphics (HD 4200) while using a Supported GPU Card (RX460). I don't believe you can install two different AMD Drivers (One Legacy and one Non-Legacy AMD Driver), one for the HD 4200 and one for the RX460 at the same time. I could be wrong, but when a Laptop had the same setup with a unsupported APU and a supported GPU card, the Users needed to use a complicated work around to get both AMD drivers to work in the same laptop.
You can try and disable the Integrated Graphics in BIOS and see if you can install the RX460 AMD Driver and see if it works. Just guessing though.
In my opinion, I believe your best bet is to open a MSI Support Ticket and AMD Service Request and asked them what they recommend to be able to have two different AMD drivers on the same motherboard.
The RX 460 AMD Driver doesn't show that it is compatible with the Legacy HD 4200 Integrated Graphics. And the Legacy HD 4200 is not compatible with the RX 460 GPU card.
You need to allow Windows 10 to install the correct AMD Driver for your integrated HD 4200 since there are no official AMD Drivers for that legacy graphics under Windows 10.