Ever since AMD and ATI married their fortunes together (pending regulatory approvals), an Intel-NVIDIA hookup has made sense to some people. If AMD can justify buying a GPU and chipset maker, the logic goes, why wouldn't Intel want to do the same thing? And this week, that rumor has been making the rounds at trading desks and analyst offices, not just around the hardware enthusiast community, giving the idea a bit more credence than it otherwise might have. In Wednesday last week, NVIDIA shares climbed 8 percent on buyout speculation plus an unrelated analyst upgrade.

But there are a couple of solid reasons to think that this deal won't happen. First, as we pointed out before the AMD merger, NVIDIA is darn expensive compared to ATI. ATI sold for $5.4 billion, while NVIDIA trades at $11 billion today. Subtract about $1 billion in debt-free cash, tack on a 20 to 30 percent buyout premium—because investors want to profit from any buyout before giving it their stamp of approval—and you end up with a $12 billion to $13 billion price tag for a company with about the same annual sales as ATI, albeit with tighter operations and better cash flow. Finally, Intel could do a stock-based deal if its own shares were trading at attractive price levels, but that's sadly not the case: INTC can be had for 25 percent less today than last December, and after a depressed summer, the stock only recently climbed back to where it was in early May. Scratch that idea.