Kaane, you tried running FURmark or similar test for a few minutes? Because I don't think your cards will survive long at full load without cooling of the pulse chip (the one that says Vitec). The stock cooler pushes ALL air past this little chip, and I've tried everything to make a HD4870CF work with aftermarked air coolers, not possible with halfway silent fans. That chip just overheats and shuts the card down, resulting in a blackscreen. I would not advise anybody to run GPU-only waterblocks without proper cooling of the PWMs an pulse chip.