Water blocks are essentially the heatsinks of water cooling. These are what mount directly to the heat producing parts your cooling. The most common blocks used are for the Processor and Graphics card. There also exist blocks to cool other chips on your motherboard, your memory, and your hard dives, among other things. However these are generally unnecessary and won't be covered in this guide.
CPU or Processor Blocks:
By far the most commonly used in water cooling, these blocks mount to the motherboard and effectively transfer heat from the core(s) to the coolant. They often use some form of either fins or pins cut into the base to help this transfer.
There are basically two ways these blocks can be mouned to the motherboard. The first involved the use of bolts and nuts through the mounting holes, with the block held in place with thumb nuts and springs. (See below pictures of this mounting method)
The other way some blocks are designed to be mounted is with thumb-screws that tighten into a back-plate mounted on the backside of the motherboard.
The current kings of CPU blocks include:
The EK Supreme, Swiftech Apogee GTZ, Heatkiller CPU Rev. 3, and the D-tek Fuzion V2.
All of these blocks are top notch performers and each have their own characteristics.
The Ek Supreme has been on the market for several months already and used a very fine array of fins milled into it's base with water being forced through them to help dissipate heat. As a result this block is very restrictive and should never be used with more than one other block in the same loop as it.
The Swiftech Apogee GTZ is one of the newer blocks on the market and has been a hue success. It is much less restrictive than the Supreme and features and dead simple mounting setup. It performs just about on par with the Supreme and has the good looks to boot. Also, works very well with i7 processors. This block utilizes a base with very tiny pins in the middle.
The Heatkiller Rev. 3 is almost brand new to market and extensive testing has not been accomplished, however it is a solid well designed block. The base features cuts made into the base creating fins.
Lastly, the D-tek Fuzion V2 is another great block. However, it does not perform as well as the other in applications where a quad core processor is involved. It's forged base features an array of relatively tall pins in the center.
As before with the pumps there also exist a couple budget blocks that offer good performance at a great price. The First is the XSPC Delta V3 block. This block offers great value for money and will handle any processor with ease (i7 chips will benefit from the more expensive blocks outlined above.)
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The Second budget blck is the OCZ Hydroflow. Made by the same people well known for their Memory, the OCZ Hydroflow is based in part off older Swiftech blocks and is a decent block.
OCZ OCZTHYDF HydroFlow HF-MK1 CPU Waterblock Retail at ZipZoomfly
Graphics card blocks:
Graphics card water blocks come n two basic varieties. Full cover blocks, and core only blocks. A full cover block effectively covers the entire side of the pcb that the core is on. These blocks are large, heavy, and expensive. They do however offer the cleanest solution to keeping the card cool, and are often the only way to easily water cool multiple cards. Some of the more common manufacturers of these blocks include EK, a company based in Slovenia, Danger-Den, the company that first pioneered this style of block located in Oregon, and more recently, XSPC. This style of block is also the only kind available to cool multi-pcb cards like the 9800GX2 and the GTX 295. The one problem with full cover blocks is they are machined to only fit onto a single model card. Manufacturers often make cards with non reference layouts, because of this, these cards are often not compatible with full cover blocks. (See the pictures below to get an idea of how these blocks work.)
Core only blocks are a cheaper and less elegant solution to cooling a video card. These more closely resemble a normal CPU block and only cool the GPU itself, none of the rest of the card. Because of this, ramsinks and power regulation chips will need to be cooled. This is often done with ramsinks, small rectangular heatsinks with Thermal tape to attach them to the chips. These core only blocks are much more likely to remain compatible with other models of cards. Most available today will work with cards all the way back to the 6 series of Nvidia cards without issue. These blocks are also significantly cheaper than full cover blocks.
Some of the more popular models include the D-tek Fuzion GFX V2, and the Swiftech MCW-60.
Both these blocks offer comparable performance and restriction and come at a similar price point. It really just comes down to user preference on which one to buy.
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