Ran it for half an hour or so and it has made a difference. It still unfortunately shows a bit brighter down the left edge and a bit dimmer on the right edge. The vast majority is pretty good.
The Lenovo I picked up unused in a sealed box seems fine. An i5 with 8gigs and 2Tb, it has an NVidia something or another which I've connected via an HDMI lead.
My one disappointment is that I'm not able to go to a higher refresh rate. Perhaps it's limited to the card but a review on the monitor didn't cover that issue. Funny review - they waxed lyrical about the Dell Ultra Sharp 2408WFPb for most of the review but the last couple of paragraphs said it wouldn't do for serious photographic work and this and that was not so hot. It was as though someone else had finished the article.