There are a few typical reasons for what nVidia is doing. One is cash flow. Someone in another thread was equating cash flow with profit. One has
absolutely nothing to do with the other.
Cash flow is what meets your monthly (or daily, if you prefer) expenses. If you have a payable acct. for $100.00. You need $100.00. It doesn't matter if you made profit while you acquired that $100.00. You just need a hundred bucks. You can acquire it simply by liquidating assets. It will meet the purpose of paying the bills.
If nVidia (or some other fictitious company if it pains you to look at nVidia this way.

) has $100K in fixed expenses per month, just to apply a nice round figure, then they must somehow come up with that money each and every month. This is before they concern themselves with making a profit.
Let's say that on avg. nVidia grosses $100 on each card they sell. In the end this gets them $20 gross profit on each card. Well, the first thing they need to do is sell 1000 of them just to pay the bills. They haven't actually made anything off of the cards yet, but they've paid the bills. (There is a point where they actually make ~$20 off of each card, but the math pains me to think about it right now. IIRC it's at about 100K cards, but don't ask me to prove that number.)
Now let's assume that nVidia isn't selling 1000 cards a month. They can't pay the bills. Even if those cards cost them nothing, they still haven't generated enough cash flow to pay the bills. Suppose they drop them to $50 a card and sell 50K cards? They lost $30 on each card but paid the bills with $150K capital left over. In the short term, this could be a positive thing to do. It gives them working capital. Now, you can't do this indefinitely, but sometimes it is a smart business move.
Another reason is just to get rid of something at a loss now instead of waiting because it's value is going to drop dramatically before you could sell it at a profitable price.
There's also end of fiscal year (or quarters) antics and balances of assets to expenses and inventory to inventory turns, etc... September is the end of an important quarter. You need to have your business in good financial shape for the forth quarter of the calender year. For the Christmas season. nVidia screwed up last Christmas. They don't want to do it again. They don't seem to be too well set this year either, product wise anyway. They need to do whatever they can to take advantage of Christmas and hopefully align themselves to stay viable until they do get back up to speed with their technology.