AMD (AMD) just hit a milestone that would have seemed unlikely a few years ago. For the first time, it controls more than 30% of the market for x86 client CPUs, the chips that run desktops and laptops. According to Mercury Research, AMD’s share reached 30.3% in the second quarter, up from just 21.1% two years ago. Intel (INTC) still holds the rest at 69.7%, but that share has been dropping lately. AMD gained ground in desktops, laptops, and servers all at once. Although AMD’s desktop share climbed to 34.9%, the desktop market itself shrank more than 20% last year. The fall was primarily due to soaring memory prices that have made new PCs more expensive. AMD gained share because its shipments held up better than Intel’s. So this was a share gain in a shrinking market rather than a demand boom.