Theoretically, if you mount a waterblock on your mobo and remove the original heatsink, you won't loose your warranty - just recently read that in one of the threads here...
However, the key is to remove the original heatsink in a way that you have to be able to re-mount it if you need to RMA.
In the case of the R5E10, this is very hard to do if you also want good look... The original I/O block is looking good, but there is a heatpipe inserted in its bottom... it is hard to pull it out intact... I just simple cut it - but then I lost the warranty... c'est la vie...
Loosing your warranty is part of the watercooling experience... at least I considered so (never RMA'd a component hurt by water)...