You could if you did a full loop. Adding a gpu water block would make it virtually single slot card, giving enough room for a slim 240 radiator and slim fans still with several mm of clearance to allow air to get to the rad. For the CPU, a great choice would be a water block and pump combo but a small pump to put near the power supply may work. A reservoir may be hard so a T line might work best, but if you can, a reservoir makes filling and bleeding much easier.