Shoehorning Duallies - A Slightly Bigger Build

 

My previous compact dual cpu builds were based around the (now long discontinued) Coolermaster Elite 360 and motherboards that were more or less ATX sized - or SSI CEB which is a little deeper at 10.5 inches rather than 9.6. At 147x380x410mm (WxHxD) the case comes in at 22.9 litres in volume and had two 5.25" bays and two 3.5" bays which provided ample room for storage (and judicious routing of cables). However, those were sold off a while ago.

Looking to reduce my power consumption a bit, now that utility bills are rising, I decided to consolidate my desktop and server machines into a single unit running Linux/KVM. This would need to be quite a beefy unit but I don't want anything too big. Shopping around, I came across the Kolink KLA-002 at overclockers.co.uk which looked rather interesting. At 175x410x385mm (WxDxH) and 27.6 litres, this case is about an inch wider than the Elite 360 but can fit an EATX motherboard with some adjustment. It's also dirt cheap so I'm happy taking a drill to it.

It looks like there are two optical bays up top but the upper bay is blocked by the front panel buttons etc. moulded into the top of the front cover. You could mount an internal drive or two there but I am going to tuck the extra length of the PSU cables in there to keep things neat. 

There are two 2.5 inch mounts on the base plate in front of where an ATX motherboard would fit - however, these would be blocked by an EATX motherboard. There are screw holes at the bottom left of the case to fit either a 3.5" HDD or a 120mm fan (albeit with a fairly restrictive grill). 

There are also two 3.5" drive bays at the bottom right which will need to be removed to get a larger motherboard in. It is possible to slide a board in behind the drive bays but you risk damaging components and reaching any connectors there is impossible. 

To remove it you need to drill out 5 rivets (arrowed). Two on the bottom edge, two under the front cover and one on the base. They can easily be replaced by a screw and a nut if you want to reinstate the bays later. 

Once the bays are removed there is space for an EATX motherboard with some caveats. There are only standoffs in the ATX board positions so you will need some additional board support. You can get plastic standoffs that clip into the empty screw holes but even then the bottom right corner position falls over a hole in the backplate for cable routing. If the board is the full 330mm deep then it will come right up against the front fans which can be tricky if there are, for example, right angle SATA connectors there. In that case, consider investing in slimmer 120mm front fans.  

 
The motherboard I chose for this build was the Huananzhi X99 T8D. Huananzhi is one of the better home-grown Chinese manufacturers who tend to have reasonable VRM designs, functional BIOS's and even a degree of support. This is an unusual board which targets the small number of non-standard OEM Haswell Xeons that support DDR3 as well as DDR4. These were adopted by the likes of cloud providers back in the day so are plentiful and cheap on the second-hand market. Huananzhi have also added some more modern features - bootable M.2 slots for NVME and SATA SSD's, USB 3, onboard BIOS code indicators and onboard power and reset buttons for testing. It also has 7.1 audio and dual (Realtek) Gigabit ethernet. The board is also a fraction smaller than EATX at 290x310mm which makes fitting it into the case a breeze.

To go with this board I have two Xeon E5-2696 v3 CPU's with 18 cores each and a top turbo speed of 3.8GHz. These can be had for under £100 off Aliexpress which is ridiculous for the amount of power you get. Each of the E5's has a multicore Passmark score equivalent to an Intel Core i9-10900K. There is a BIOS mod which will allow the full turbo speed to be applied to all the CPU cores but this can strain the VRM's somewhat. This mod works for all V3 Xeons - search for "S3TurboTool" if you are interested. Usefully this motherboard also supports LRDIMM's which are also remarkably cheap since not all motherboards support them. £260 for 8x32GB DDR3-1600 LRDIMMS from the well-known auction site, which happily overclock to DDR-1866 speeds.

Getting back to the build, all the front panel connections are on the bottom edge of the board. Rather than messily routing the cables through the case, they can be bundled together and fed through the holes in the front of the case cleared by removing the drive bays. All except the USB 3 connector which is too big. This is fed through the slot under the optical drive and tucked out of the way under the bottom edge of the front fans. There is just enough room for the cables round the edge of the optical drive when the front cover is snapped into place. I've also put in some mesh filters over the fans since they are intakes. 

Here is the motherboard fitted into the case. Huananzhi provide suitable plastic standoffs for cases that don't have standoffs in the right place.

The coolers are Raijintek Aidos with the fans replaced with 90mm Arctic PWM PST ones. One annoying feature of the motherboard is that it only has 4-pin fan control for the CPU fans. The PST feature of Arctic fans allows the PWM signal to be passed on to other fans. The front CPU also controls the two 120mm intake fans - which are also Arctic PST models. The rear CPU initially also controlled the rear exhaust fans - two Arctic 80MM PST models that I found got a bit noisy as things warmed up. I ended up connecting the rear fans to one of the 3-pin fan headers with a speed reduction resistor. The fan speed vs temperature profiles for each CPU can be independently configured in the BIOS and it actually works! Unfortunately, the profiles rely on chipset temperature sensors rather than the CPU sensors so there is a bit of a lag in their response. Linux fancontrol can be used to get round this.

The two 8-pin EPS power connectors and the main ATX power connector are all at the top edge of the board so those cables can be tucked above the DVD-RW drive. I found that one of the EPS cables could be fed through the channel on the side of the 5.25" drive bay. The other could be tucked into the gap between the case and the PSU and then down the gap between the PSU and the rear fans. 

The only cables I routed behind the motherboard were the SATA data cable for the DVD-RW drive, and the SATA power for the SSD's. As I've mentioned before, I find the SuperMicro slim SATA cables to be the best for my purposes. You could also run a GPU PCIE power cable down here if needed - I chose a GTX 1650 card which doesn't require a power cable and provides enough oomph for the few games I do play, like Oolite or a bit of Minecraft.

You can also just see the PST signal cable from the front CPU fan which also connects to the two front fans back here.  

Having removed or blocked most of the storage bays in the case, I do need to have some more storage slots than just the on-board M.2 connectors. On the well-known auction site, I found a card that holds two 2.5" SATA drives and fits into a PCI slot. It doesn't take any power or signals from the slot - there are two SATA data and one SATA power connector on the card edge.

Two drives aren't really enough though, so I bought two cards, removed the bracket from one and stacked them together using 8mm spacers and 25mm screws. This gives just enough space to fit a 7mm SSD and four of them occupy a slightly-larger-than-single-slot card. Just found an "official" but bulkier version from DeLock.

 I did have to saw/file off a few of the PCI slot fingers to fit round motherboard components but since there are no connections there it is not a big deal. You can see it fully loaded at the bottom of the whole-case shot above.

I like to have one physical drive per VM using KVM raw pass-through. Easy to move to a new host and there is no storage contention when VM's are doing heavy activity. 

 So there you have it:

2x18 Haswell Xeon cores at up to 3.8 GHz

256GB 8-channel DDR3 1600 LRDIMMS overclocked to 1866

1xM.2 NVME SSD + 4x2.5" SATA SSD's

All in a 27 litre case, and costing well under a grand.