It could be that your PC is having video issues booting. Find another monitor and see if it displays correctly. If it does, your original monitor is defective. If it doesn't, your PC boot has video issues (bad drivers, recently installed software causing conflicts with video card, etc.)
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It could be that your PC is having video issues booting. Find another monitor and see if it displays correctly. If it does, your original monitor is defective. If it doesn't, your PC boot has video issues (bad drivers, recently installed software causing conflicts with video card, etc.)