Spire Fourier IV heatsink/fan

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The stock 92mm fan is made by Fanner Tech (otherwise known as Shen Zhen), model FD09025B1M. The B in the model name means ball bearing, and M means medium speed. The combination of ball bearings and clear plastic is not promising. We have yet to encounter really good acoustics in any clear plastic fan, and few ball bearing fans have good sound quality.

We're always leery of clear plastic fans.

The fan controller is a genuine voltage regulator. It's similar to the circuit found in the well-know Zalman Fanmate. It has a pass-through for fan rpm monitoring. The circuit and control knob are mounted on a PCI slot cover plate which it is meant to replace so that you can control the fan speed by reaching behind the computer. For a DIYer, it would be a simple matter to remove the control from the PCI cover plate and install it in the front of the case for greater convenience.

Fanmate-like fan control circuit.


The Fourier IV is small enough that on our test motherboard, it could be mounted in three of the four orientations. The heatpipes interfered with the northbridge heatsink in the fourth position. In the opposition position, the heatpipes hung only about half a centimeter over the edge of the motherboard. With most cases, there is a bigger gap than that between motherboard edge and bottom of PSU. Fit should not be an issue in the vast majority of systems.

Installing the Fourier IV on our test bench socket 775 motherboard was as expected for a through-the-motherboard bolt mounting system; it's a bit of a pain. The bottom backplate is insulated on one side with rubber, and it's smooth, which means there's no way to make it stay in the right position while you maneuver the heatsink on the top side of the motherboard to get its mounting holes in the right place. The machine screws go in from the trace side of the motherboard and thread into the lugs of the heatsink.

The job would be very awkward for one person without some tool to hold at least one of the items still — preferably the motherboard. I had help: Nick Geraedts' two hands to hold the board and heatsink, and his eyes to tell me when the heatsink was in the right place while I positioned the bottom plate and used a magnetic head screwdriver to tighten up the screws. Captive screws in the backplate would have helped.

It was awkward to hold backplate, motherboard
and heatsink in place while trying to insert a screw with screwdriver to go through holes that needed to be lined up in all three items.

Just how tight to do up the screws was also an issue here. There is no positive physical stop or guide. Not enough or uneven pressure means poor cooling. But overtighten a screw mount heatsink like this one, and you can crack the motherboard. It could be the smallest of micro cracks, but if some key trace in one of the many layers on the PCB gets broken, you end up with an intermittent motherboard useless for a testing platform. It's the way at least one of SPCR's previous test boards was forced into early retirement. (That and the many dozens of times heatsinks and CPUs were installed and uninstalled on the board.)

Such "how tight is tight enough?" issues for bolt/screw mounting are completely solved by the pre-loaded spring-in-bolt system used on heatsinks such as the Thermalright Ultra 120, the Apack ZeroTherm BTF80/90, the S-PAL8952 by Alpha Novatek, who first brought the concept years ago to large CPU heatsinks, and finally the Swiftech MC462, featured in the very first review of heatsinks at SPCR. The MC462 still had four bolts and nuts, but Swiftech did it better than Spire even back in the stone ages of 2002.

Never mind, deal with the here and now. I turned to the manual for illumination. None was to be found. The manual stated the following:

"Fit each of the screws to each post. Do not tighten them fully until all have been tightened equally cross ways. Note: Rule of thumb is, fully tightened is sufficient. Do nut (sic) use a lot of power to fix the screws into the back-plate. Doing so might brake (sic) or even your motherboard which will not be covered by Spire's warranty policy."

That's not helpful at all, is it? Each of the second and third sentences alone is vague, but the two together are downright cryptic. We're left grasping for the meaning of fully tightened.

The gap between each corner lug of the heatsink and the motherboard.

I examined the way the heatsink sat atop the CPU before being secured down. The photo above shows a small gap, perhaps 1/16" or a touch more, between each mounting lug and the motherboard. I wondered if this gap was small enough to allow each screw to be threaded as far as it could go. The stiffness of each steel lug was checked by pressing against them. They seemed extremely stiff. If the screws were done up all the way, the pressure against the CPU and the motherboard would be enormous. A hard spacer washer of the right thickness (between motherboard and HS mounting lug) would have been helpful, but I had no way to judge which of the washers in my bin would be the "right" thickness.

In the end, I decided to leave a small, even gap all around the four lugs. With only a visual check, this was not easy to do, especially as the screws go in from the underside of the motherboard. Afterwards, I crossed my fingers when I booted up the system. Happily it booted up fine, but I am not happy about the installation procedure or the instructions. Both need some serious attention!

Safely installed, but not without a lot of hassles and worries.

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