Instructions
Locate the information label on the box that your Xbox 360 Pro is packaged in. This label could be in a few different places. It is a white label with black lettering that details information specific to the Xbox 360 that is in the box you're holding, like its serial number.
Look at the "Power Voltage" information on this information label. If the power voltage is listed at "12V," you are likely holding an Xbox 360 Pro with a Jasper chipset.
Find the "Lot Number" on this information label. The "Lot Number" will be toward the bottom of the label, and will be four digits. The lot number for the first Xbox 360s with a Jasper chipset was 0843. If the lot number on the box your holding is 0843 or a higher number, you're holding an Xbox 360 Pro with a Jasper chipset. If the number is lower, you have an older model Xbox 360 Pro.