The original Xbox from Microsoft was basically a slightly modified x86 computer (complete with actually-usb-ports-with-a-proprietary-plug controller ports)[0],

The original Xbox from Microsoft was basically a slightly modified x86 computer (complete with actually-usb-ports-with-a-proprietary-plug controller ports)[0], where the 64mb of DDR SDRAM was soldered directly onto the motherboard. Now, it's widely known within the Xbox "scene" that the quality of the RAM fluctuates a lot between different machines. The speculation was that Microsoft bought the cheapest bottom-of-the-barrel RAM it could find in bulk, which meant they couldn't hardcode the memory timings. Instead, on boot, it clocks the RAM at the highest speed and does a quick write-and-read test. If it fails, it clocks it down a step and repeats the test until it finds a stable frequency. This explains why sometimes the same game would run perfectly on one Xbox while stuttering on the other one, even when swapping DVD drives. [0]:https://en.wikipedia.org/wiki/Xbox_technical_specifications https://en.wikipedia.org/wiki/Xbox_technical_specifications