They didn't use to be. I have used several of the old socket7 motherboard over the years, and they worked fine. Admittedly, often better in Linux then Windows, but this is not completely unexpected.
However, their later offerings seem to be getting less and less reliable. take, for instance, the pair of M810LMR athlon boards I got about 10 months ago. Both worked fine originally, but have degraded more and more over time. Both were set up identically, with 32MB Geforce2 cards, 1GHz durons, 256MB sdram, 40GB hd, CDrom, etc, as cheap games machines. They worked really well, at first.
One of the motherboard ate two 1.4GHz athlons in a row, as soon as the power was turned on. I finally came to the conclusion that, no matter what the manual said, they were duron only. Not really a problem, though, since the durons were fast enough for the purpose.
then they started getting less reliable. Locking up randomly, taking several tries to boot, and so on. At first I though it was simply windows decaying as it often does, and reinstalled both machines. No luck, the same problems recurred. One of them has now got to the point that it won't boot at all, and refuses to run windows 2000 setup or a linux installer, and the other one dies every half-hour or so.
Anyway, I'm binning both motherboards, and won't be buying more from that manufacturer. I'll stick with Asus, MSI, or Aopen from now on. They actually work!
Irritated, and had to get it off my chest
pca