I misspoke, the cables I bought were DVI-D, not DVI-I. Is there a way to edit my first comment?
Amazon replaced my first defective cable, so later I bought a second identical one. But it was completely dead (the first one was intermittent). I'm getting a refund on that one. About Amazon reviews, I always read the negative ones first, and check the % of negative reviews. That's why I came here to ask the question, all I could see on Amazon were no-name brands.
My monitors are Samsung, bought used to they didn't come with cables. But thanks for that idea, it's a good starting point. I searched through Google and it brought up a Samsung cable selling on Amazon. I went to Amazon and tried searching for Samsung DVI to DVI cable, and the first DVI to DVI cable was 19 entries down. That's how screwed up (and manipulative) the Amazon search function it. I gave up after 57 entries, 3 DVI to DVI cables, and no Samsung.
I just found a bunch of Samsung DVI cables on eBay, longer cheaper than the Amazon one and with free shipping. Warranty probably won't be as good as Amazon, but for $7 it's worth the risk.