When it comes to air cooling, there are a few companies to keep in mind while shopping for a heatsink. Swiftech is one company that I always consider when I need a cooler. Other than being excellent performers, their heatsinks and waterblocks are of extremely high quality. This quality doesn't come cheap, but like the old saying goes, you get what you pay for.

With the MCX4000, what you're paying for is the largest Pentium 4 heatsink we've ever worked with. Unlike the MCX462, which can be customized to fit on Pentium 4 motherboards, the MCX4000 has been built from the ground up for the Pentium 4. Well, I guess it really isn't built "from the ground up", since the underlying technology behind it follows the design philosophy of the Athlon MCX series, but just in case clarification is needed, this is a P4-only cooler this time around.

Specifications

Heatsink

Base: CNC machined, C110 copper base, 3.14"W x 3.5"L x .375"H, flatness better than 0.001", micro surface finish 8 or better.
429 Helicoid Pins made of High Thermal Conductivity Aluminum Alloy, press fitted in the base.
Overall heatsink dimensions 3.14"x3.5"x1.55"
Weight: 21 oz (600g)

Retention mechanism

Motherboard fittings: 6-32 Female to Male 1/4" aluminum round standoffs with nylon washers and nylons nuts
4 compression springs providing exact specified pressure per chip manufacturers.
70mm and 80mm fan mounting screws

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The MCX4000 comes neatly packaged with mounting screws for 70mm and 80mm fans, lock nuts, thermal paste and mounting screws. The mounting screws are actually pre-installed, which will save the user a bit of time. Although I'd normally say generic thermal paste is generally as good as premium pastes, it is a nice bonus that Arctic Alumina is packaged, as application and performance is pretty good.

I should note that officially, the model we've received is referred to as the MCX4000-B. Earlier models of the MCX4000 included a TMD fan (we looked at those in our Aeroflow reviews), but the early TMD fans had major issues, notably fan failure. Swiftech now sells the heatsink separately, but you can easy install most aftermarket fans without any issues. If you want to check out Swiftech's statement, you can read it here.

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The MCX4000 will almost certainly require removal of the motherboard, and mounting plate that is stock on Pentium 4 motherboards. Although this will be a nuisance for some, the mounting mechanism Swiftech uses will pretty much insure a secure installation.

An issue with mounting previous Swiftech coolers (that required the 4-hole method) was that the nylon hex nuts they've provided in the past were easily stripped. The reason this would happen was because in many cases, removal of the cooler (perhaps to change a CPU or reapply thermal paste) would almost mean removing the motherboard again because the hex nuts beneath the motherboard would loosen and it would be impossible to tighten the mounting standoffs into them again. This would be remedied with a dab of crazy glue, but Swiftech came up with a more elegant solution. I inquired about this, and they sent me this email...

"The hex nuts are "locknuts". They feature a nylon insert that locks the nut to the screw, and further prevents it from spinning upon disassembly. Nylon insert side should be pointing towards the outside. Tightening the nut requires a 5/16 socket, or a pair of thin nose pliers. New stainless stell standoffs are much stronger, no chance to break them :-) This assembly completely eliminates the standoff spinning when the HS is uninstalled. You can also use a 1/4" socket to tighten the standoff itself."

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As with all the MCX coolers, the pins are ridged, aka helicoid. This helicoid pin design increases surface area for heat dissipation. According to their specifications, the pins increase air turbulence for more efficient heat dissipation compared to traditional fin design. We've pointed out earlier that the MCX462 could be modified to work on Pentium 4s. The pin count for that cooler was 371 helicoid pins. The MCX4000 is bit larger, and increases the pin count to 429.

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The copper base measures 3/8" thick. There's a heat spreader as well that lines up perfectly with the Pentium 4. The heat spreader has been machined flattened to 0.001", and a micro surface finish 8 (or better). I couldn't detect any defects, and it has a nice mirror shine to it, though the surrounding area seems a little rougher. This isn't a concern though as this area never makes contact with the CPU.

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Given the enormous size of this heatsink, physical compatibility is a concern. The heatsink itself is about the size of the Intel heatsink retention plate, so I don't expect any problems fitting on the motherboard. Pictured above is the MCX4000 installed on our MSI 845PE-FIR. The heatsink is for Socket 478 motherboards only, and it will not fit on older Socket 423 motherboards.

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