I'm not sure on that. Look at what sidehack was able to do with a chip. I mean it's able to do 8GH easily with no issues.
While the Compac will run passive at 8Gh/s, I wouldn't really recommend it - never mind if putting it into an enclosed space with limited surface area for cooling (which the R1 largely appears to be, ventilation holes notwithstanding).
Mine was outside I give you that. I did add PC fan's to the area and have OC'ed them after to 15 gh. If they have clocked at around 5 there it likely will never get hot.
I would rather have a fan on R1 with a little more power. But guess for a router their design is much more common. I do look forward to mods on it