If you have the GPU heatpipe with the newer, copper extension with THAT manufacture date, it's been sent in to be fixed. There is no other explanation. UNLESS, the case you have with that particular motherboard has been swapped for another, older, case. Nothing else would explain why that newer heatsink is there. btw, Zephyr has HDMI........so it can't be a Zephyr with that manufacture date. You have a Xenon right now, unless it WAS sent in for repair at one point. Then there is a small possibility it could be an Opus (Falcon board with no HDMI), inside your old Xenon case.
Basically, if that isn't an Opus, there is pretty much no chance that the X-clamp replacement method will last. I'm just assuming that is what you did. Still, anything else will probably not last either. If it is a Xenon, your fix is temporary and it MUST be reballed to last long at all.