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#11
That's why I would suggest another monitor to test. If it is ok on a different monitor the NEC may just be incompatible. It seems you have tried everything I could offer as I don't know precisely what is in this custom build in an HP case. If a video card is installed I would need to know what model. if it is integrated graphics (built into motherboard) I would need Motherboard Model. We could try updating the graphics drivers but again it would be best if we knew what type and model numbers we are talking about here. Any warranty on the custom build? Might be a good idea to contact that shop and see what they can offer.