Why can't manufacturers of video cards use decent fans. Every card I've tried gets noisy within two month. I keep it clean and inspect it so it's not from dirt. Any suggestions. TIA

I feel your pain. I note the same problem with many chipset fans too. As far as suggestions, there are none other to keep a spare [quality] fan handy. Note that it would not be from dirt itself as the fans use sealed bearings. Now if dirt is allowed to build up such that it restricts movement of the fan, that may cause the fan to overheat, which could damage the bearings and start causing noise. Generally it is just as you suggest, lousy fans to begin with.

That said, 2 months for "every" card if not right, and I suspect an exaggeration. If not, then I would check your PSU voltages to make sure they are not too high, causing the fans to run faster than designed to tolerate.