[ben333]

Does it cool your CPU and GPU fanlessly already? Thats pretty impressive, what temps are you getting? I wouldn't waste my money on a steel harddrive block... You can't overclock a hard drive and they usually don't get too hot in a well vented case so I wouldn't bother watercooling it. If the pumps have different flow ratings I think its possible they can damage something so you'd probobly want to replace the one you have or add an identical one. For quiet and powerful I'd recommend a mcp655 but they are a bit pricey.