[David M]

Generally the vendors will tell you on their website what cooling blocks will work with which motherboards. If it is not listed on the website, then you can call the vendor. I have had really good service with Dangerden and Koolance on the phone.

As far as pumps go, you can only push so much water through tubes before you start to get so much pressure that you increase the risk of blowing a tube off a cooling block nipple...or springing a leak. Therefore the greatest factor for pumps is reliability and much less so pressure. If you want more flow volume then buy larger diameter tubing. It's my opinion though that 1/2 inch tubing is overkill because you are only removing a little over 100 watts of heat at most from any one heat source and heat removal is bottlenecked by the surface area of the cooling block and not by the volume of coolant flowing through the heat block. Per amount of volume, water holds a LOT of heat therefore it does not take much water flow to remove a lot of heat. All that heat still has to flow through the heat block which are relatively small..so there is your heat bottle neck. 3/8 tubing has a shorter bend radius which makes routing the tube in tight quarters much easier.

You can buy the heat blocks with the 1/2 inch nipples and then boil the end of the 3/8 inch tubing for about a minute and quickly slip it over the 1/2 inch nipple. Practice doing this a few times though. You get the best of both worlds this way...a nipple with a 3/8 inch INSIDE diameter and tubing with 3/8 inside diameter. Dont ever expect to be able to slip the tubing off the nipple though. It has to be cut off. Buy Tygon tubing...it is more resistant to kinking than the cheap stuff sold at the home stores.

Do you have a parts list for your cooling system? If so, what do you have so far?