Laptop screen banding, blur, poor quality

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Hi, sorry, not strictly a monitor but still... need some help. There's got to be something missing here. Problem is vertical banding, poor gradient quality, blurry text and fringing around letters. In short poor picture quality. Tried 2 replacement screens from same maker Innolux as well as Samsung. No change.
There may be some incompatibility between LCD and BIOS... some suggest dithering status=unknown. This has been since laptop was new.
AMD A6 6130 Radeon R4
What would be the best way to troubleshoot, test and define the problem?
If screen is not exchanging full info with BIOS or video card or for some reason they are unable to successfully communicate, then LCD will not do what it's supposed to do. The key is diagnosing the problem. Was considering using CRU to try different refresh rates but I don't have a full understanding what to expect and how to probe the LCD. Would love someone to chip in and give some guidance.
Thanks.