Alternatively titled Doing buck-fifty on the DMI

I'm putting together a home server to take over for my long-serving Synology NAS that can no longer manage my ever-growing hunger for data. It's also getting a bit slow, and I'm looking to host more services for myself. The new machine will run Unraid and serve as a NAS device, a Jellyfin server, and as a Docker host for whatever I may dream up. Maybe a VM at some point as well.

Most of the components I already have, but I'd love to hear any advice you may have on how to arrange them on the motherboard. First off, here's what I'm looking at:

Parts

Essentials

Case Fractal Design Node 804

Power supply Corsair RM750x

Motherboard Gigabyte Z590M

CPU Intel i5-11600K

I was initially looking at a 12th-generation Intel system, but ended up going with the 11th generation. This is in part due to finding a deal on the motherboard and the processor and wanting to avoid some C-state-related pitfalls I've read about (michaelstinkerings.org). As I'm building an mATX system, I want to make the most of limited expansion slots. Given the number of hard drives I've planned for it may sound silly, but I want to save power where possible. The machine is primarily for my household's use, I don't expect heavy use all day, so it should be able to sleep when it's not in use.

(For memory, I'll be using a 16 GB set of QVL DDR4, unless the off-QVL set of 32 GB DDR4 ends up working. Currently having a bit of trouble finding a QVL'd 32 GB set at a sensible price.)

Storage, array

A motley collection of SATA3 HDDs, mainly used/recertified drives. When I first power the system on, it will likely contain the following:

• Four 5400 RPM 4 TB drives from my current Synology NAS

• One 7200 RPM 16 TB drive

• Two 7200 RPM 18 TB drives (one of which will be used as parity)

Going forward, I'm planning to get more drives in the 16-18 TB range as I find suitable deals, first to fill out the Node 804's two four-drive HDD racks and then to begin phasing out the older, smaller drives. At some point, I would probably also add a second parity drive. The array will mostly be used for media files.

Storage, SATA SSD cache pool

A set of four 1,92 TB SATA3 SSDs in the case's forward 2,5-inch bays and on the bottom of the motherboard side of the case. This would be the primary destination for any new files coming in to the server before being shuffled into the array.

That's too many drives!

Sharp-eyed readers may notice that the SATA drives listed thus far tally eleven in total with one more planned, while the motherboard only has six SATA ports. I intend to connect some of these drives using M.2 and PCI-E adapters based on the ASM1166 chip. More on these below.

Storage, NVMe SSD cache pool

Two 1 TB drives, one PCI-E 4.0 and one PCI-E 3.0. This is for application data and anything that needs faster storage.

Auxiliary devices

MZHOU PCI-E SATA controller (ASM1166)

Bewinner M.2 SATA controller (ASM1166)

EZDIY-FAB Quad M.2 card

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Putting it all together

The fun stuff. The Unraid forums have been a great source of information and inspiration, and I'm hoping I can cajole some of you to advise me on final assembly. With your help, I can maybe avoid at least some trial-and-error. As the topic title suggests, my biggest question has to do with PCI-E lanes: those on the CPU, those managed by the chipset, and the DMI link between these two. JorgeB's SATA controller testing thread has been very helpful, but I'm still not entirely sure on my setup. Here's what I have on that:

Traffic management

Here are the connectors on my motherboard, and how I envision using them:

• PCI-E 4.0 x4/x2 (M.2 slot, CPU)

  • SATA controller connected to the SATA SSD cache pool

• PCI-E 4.0 x16 (PCI-E slot, CPU)

  • Quad M.2 card (x8x4x4 bifurcation) hosting up to three drives for the NVMe SSD cache pool

• PCI-E 3.0 x4/x2 (M.2 slot, chipset)

  • One drive for NVMe SSD cache pool

• PCI-E 3.0 x1 (PCI-E slot, chipset)

  • SATA controller connected to two HDDs in the array

• PCI-E 3.0 x4 (PCI-E slot, chipset)

  • (2.5G NIC)

• 6 SATA3 ports (chipset)

  • HDDs in the array

The way I see it, the system will be handling two different patterns of data traffic for new files:

1. From the network interface to the SATA SSD cache

   • Regardless of whether I use the motherboard's on-board 1G NIC or a spare 2.5G PCI-E NIC (in the x4 PCI-E slot controlled by the chipset), the data is going to come in through the chipset lanes/the DMI. Thus it would make sense to keep the SATA SSD cache pool on the CPU lanes via the M.2 slot.

2. From the SATA SSD cache to the HDD array

   • The motherboard's six SATA3 ports are controlled by the chipset, so it makes sense to me to keep the array completely on the chipset lanes by installing a PCI-E SATA controller in the 1x PCI-E slot controlled by the chipset.

The Z590 chipset has a 'maximum' of 8 DMI lanes, but I haven't been able to confirm what this specific motherboard is equipped with. If it's 8, it seems to me like it may not pose too much of a bottleneck. Even then, my thinking is to avoid running traffic between chipset-connected devices, as that could occupy lanes coming and going, which seems inefficient. The setup above was designed with this in mind: first chipset (NIC) to CPU (M.2 SATA controller), then CPU (M.2 SATA controller) to chipset (motherboard SATA ports, PCI-E SATA controller).

The last part of the puzzle is the fastest storage. The idea here is to use a PCI-E M.2 adapter in the primary x16 slot (the motherboard should be capable of 8x/4x/4x bifurcation, so a maximum of three drives and four lanes 'wasted') for this. If/when I have the chance to get more NVMe drives, I'll move the one PCI-E 3.0 drive I have to the chipset's M.2 slot, and fill out the x16 adapter with 4.0 drives. The total for fast storage would thus be three PCI-E 4.0 drives (on CPU lanes) and one PCI-E 3.0 drive (chipset lanes). These could replace the SATA SSD cache pool for incoming files, but this development is not currently on the horizon with the way prices are going.

I feel like I have a workable understanding of the CPU/chipset/DMI system and that the setup I've described here should make sense, but does it? Am I overestimating the bottlenecking potential of the DMI or missing a critical component somewhere else? All feedback is appreciated!

Edited December 28, 2025Dec 28 by computer-jeff
minor edits

You will have a decent number of spinning disks and screw them in. If you run into disk issues or choose to upgrade them, having to tear that ancient case apart each time will get old fast! Get a case with trays.