Are your monitors connected to the motherboard or the w4100 graphics card?
When you say intel GPU do you mean a dedicated intel graphics card or the integrated graphics on the processor?
Plug the monitors into the W4100, you may need to set the W4100 as the primary card in the BIOS.
set your videocard as primary in the bios settings on boot if they are showing in device manager. Another tip is AMD cards are picky on cables a lesson learnt. Check your cables & make sure if using a Dvi cable its pushed firmly in. Mine was picky till I solved mine. Cables are the most over looked part which sometimes causes the most grief for flickering & display issues unstated issue why I push it on comments on forums. Lesson learnt free advice to suggest try