5870 GPU water block - does brand/revision effect it?

yea

I think these are be the same PCB.

Some companie use different choke or caps the are different heigth but nealry all HD5870 are stil using the reference design.

The only one that come to my mind is the MSI Hawks series that is a completely new PCB or some PowerColor cards that generally use lots of different parts on the PCB with light mods to the PCB.

These XFX looks to be very close to the reference.

I'd be very careful. I know EK blocks have a compatibility chart for their blocks.

A bit of homework you should be fine.

The Ek configurator is pretty good for tracking down the part number http://www.coolingconfigurator.com/