The method used to obtain the UUID on any given device model is dependent on the hardware implementation of that device.  For MCD platform devices (e.g. MAP 1.0, MPA 1.5, MPA 2.0, etc.), all devices based on the same platform version will likely use the same method.  For non-platform devices, any method can be used.  For Windows Mobile devices, the form of the UUID is dictated by Microsoft and includes a hardware part as well as other fields that help ensure it is unique across multiple vendors and products.  On CE devices, there is no dictated format for the UUID. On MPA devices, the hardware part of the UUID is generally determined from the flash chip and will remain the same for a given device until the hardware is modified to replace that part.  On some devices, it may be based on some other hardware element that has a unique identifier in it. From an MSP perspective, if the hardware of a device is modified such that the UUID changes, then it is a different device.  On rare qccaisons, device bugs have occured in the API to return the UUID that caused multiple devices to return the same UUID.  In such situations, those devices will NOT be practically manageable via MSP, since MSP uses UUID as the primary identifier of every managed device. No methods are currently provided in MSP to deal with this situation other than a recommendation that the "old" device should be deleted to free up its license.  Note that when the "old" device is deleted, all history of that device is also deleted.  If the device has the ability to report a serial number (as many MPA devices do), then it may be possible to use this to detect a device that has changed UUID but retained the same serial number.  By using the "Last Discovered Time", you can identify which is the "old" device and which is the "new" device, so you can know which to delete.

I was told that it is more or less a serial number on the CPU chip, so the only way to change it would be to change the chip.

Actually I don't think that it comes only from the CPU. I think the memory chip's ID number also effects. We already faced some problems on MC75 and MC55 regarding to UUID numbers. Too many devices with the different serial numbers but with the same UUID numbers we had seen before.

...as far as I know so far the UUID will be generated based on a unique hardware identifier like the MAC address of the WLAN NIC, etc. Therefore I believe with replacing the PCB or a NIC the UUID of the device will change.