It is entirely possible that HP would not begin the ad campaign without a GUARANTEED warehouse full of chips. But if you are saying that HP is locking up the inventory, then that is only part of the explanation.
IF amd has the capacity, where is it? It is still possible that breakeven analysis comes into play here, and that for the manufacturing price to come down, volume production must go up, and perhaps there is demand, but not huge demand. The simplistic way of putting this is that the cost to manufacture presently is too high.
The saga continues....