I have a similar issue but with a S5520HC motherboard in a Rackable enclosure.
Rackable installed 3 x 80mm fans on the back wall connected directly to power supply though a power brake out board. They are 3 pin. Therefore they spin at 100% in a pull configuration and connecting them to the motherboard chassis fan headers with a custom enclosure selected makes them spin at 100% as well, by intel design.
The Rackable S3012 chassis, which can be seen on eBay is a half depth, 3U design. The motherboard is put in backward.. i.e. the nics and pci-e are up front, and the dual l5640s have passive heat sinks. It really cools like a 1U since the 12 drive backplane box sits on top of the board and covers about half the motherboard. so active cooling of the cpus would be difficult.
since the fans are 3 pin, would the motherboard chassis fan headers even be able to regulate the fans or would I need to find 4 pin fans?
I thought of:
1: connecting 2 of the fans to the CPU headers and attempting to have CPU temp drive the fan speeds and customize the 3rd fan in SDR
2: connect all fans to the chassis headers and customize the fan speeds in SDR by changing the sensors used for regulation giving them the CPU temp sensor number or something like that
Biggest problem I am having now is trying to read the SDR file and know for sure what it is I am editing
Additionally, since the drive box sits on top of the pci-e lanes, it has room for only 1 card on a 90 riser, so trying to figure out how to add some cards internally, but since its a half depth chassis with half that room taken up by the drive box, there is not much room to play with.
What are your thoughts guys?
This chassis has lots of power for my needs with the dual hex cores, pulls a bit more watts at idle than I would like … about 150.. with 48gb ram.. but it really is too noisy with 3x80s going full steam!!