“The motherboard design didn't change much, besides the bigger flash and what's probably the new 65nm GPU, we also see a new south bridge model...the rest (videochip, CPU, heatsinks, general board layout) seems pretty much similar to falcon boards.
It also appears there are RAM chips on the bottom of the board again (without thermal pads even)...Microsoft recently switched to RAM chips with double capacity so they could drop the 4 chips on bottom (and only place 4 on the top)…but apparently they are back (old stock maybe?). However, the type of RAM chips they use is not bound to the motherboard revision...there are falcon boards with RAM chips only on the top and falcon boards with RAM chips on both top and bottom. Same can happen for the jasper boards.”
Although the console does not physically look any different, the power supply has been changed as well. The PSU is now 150W versus 175W with the previous generation Falcon console. Here's how to tell if you've got a Jasper console via identification of the power rating on the PSU:
150 Watt Xbox 360 "Jasper" Revision Power Supply
Of course, it is too early to tell if this new revision will finally do away with the dreaded RRoD (Red Ring of Death) that is purportedly caused by faulty / defective / overheating 90nm GPUs, but it has long been rumored that this update, in addition to lowering manufacturing costs, was planned to resolve the lingering RRoD issues.