Microsoft just announced earnings for its fiscal Q4 2013, and while the company posted strong results it also revealed some details on how the Surface RT project is costing the business money. Microsoft's results showed a $900 million loss due to Surface RT "inventory adjustments," a charge that comes just a few days after the company officially cut Surface RT prices significantly. This $900 million loss comes out of the company's total Windows revenue, though its worth noting that Windows revenue still increased year-over-year. Unfortunately, Microsoft still doesn't give specific Windows 8 sales or revenue numbers, but it probably performed well this quarter to make up for the big Surface RT loss.

At the end of the day, though, it looks like Microsoft just made too many Surface RT tablets — we heard late last year that Microsoft was building three to five million Surface RT tablets in the fourth quarter, and we also heard that Microsoft had only sold about one million of those tablets in March. We'll be listening to Microsoft's earnings call this afternoon to see if they further address Surface RT sales or future plans.

Read more: Microsoft earns $4.97 billion from $19.90 billion of revenue for Q4 2013