J.C.F

My goal is to have 2 dedicate VM's with passthrough for my wife and I. Basic needs: 1st VM (1 x m.2 (barebone) ; 1 x GPU ; using the rear OI for connectivity) 2de VM (1 x SSD (barebone) ; 1 x GPU ; 1 x USB expansion card ; 1 x ethernet adapter) running plex, storage server, small web server. [not completely committed to buy and flash a GPU to have vGPU capabilities ] storage goals: 2 x nvme for VM passthrough 2 x SSD for VM Passthrough (mirror) 1 x drive passthrough for recovering backup (data recovery if need be) 2 x SSD for cache drives 1 x SSD to spin up VMs 2 x Parity drives 4-6 x storage drives Going through all the different ideas. Will the m.2 to oculink to pcie raiser/HBA really work while retaining my PCIe slots and losing 1 x m.2 slot or should I sacrifice a PCIe x 4 lane for a HBA (and lose the ethernet adapter) or bifurcate my x16 lane into x8 x4 x4 (not sure what card / adapter to use) ? And is a 20 drive setup even possible, will the m.2 to PCIe adapter to HBA to SAS expander be worth it?

i have rog viii dark hero motherboard and want to use it as a NAS. i have 2 gpu's and a usb expansion card and ethernet card. how many sata drive can i connect? will a ASUS hyper m.2 drive work? how will a m.2 to oculink adapter benefit me to add more drives using a x4 Pcie lane? Your ASUS ROG Crosshair VIII Dark Hero is actually a very good base for a DIY NAS because it has a lot of SATA ports and flexible PCIe lanes. Let’s break down what you can realistically connect and how expansion options like Hyper M.2 or OCuLink would work. 1. Native drives you can connect (without adapters)Your motherboard provides: 8 × SATA 6 Gb/s ports 2 × M.2 slots (PCIe 4.0 x4 NVMe or SATA) (@ROG) So directly on the board you can run: 8 SATA drives 2 NVMe drives ➡ Total = 10 drives without any add-in cards Importantly: Unlike many boards, using both M.2 slots does NOT disable SATA ports on this model. (Tom's Hardware) 2. PCIe slot layout (important for NAS expansion)Main slots on this board: PCIe 4.0 x16 (CPU) – GPU slot PCIe 4.0 x16 (CPU) – runs x8 if both used PCIe 4.0 x16 (chipset) – x4 electrical PCIe 4.0 x1 slot (@ROG) If you already have: 2 GPUs USB expansion card Ethernet card You’re already consuming several slots, which limits expansion options. 3. Will an ASUS Hyper M.2 card work?The ASUS Hyper M.2 x16 Card V2 can hold 4 NVMe drives, but it only works properly if the motherboard supports PCIe bifurcation (splitting x16 → x4/x4/x4/x4). Your board does support bifurcation, but there are caveats: Best caseIf installed in a x16 slot with bifurcation enabled You can run: 4 NVMe drives on one card If installed in a x8 or x4 slotThen you get: x8 slot → 2 NVMe drives x4 slot → 1 NVMe drive So with two GPUs already occupying the main slots, the Hyper card will likely only run 1–2 drives. 4. Using an M.2 → OCuLink adapter (very useful for NAS)This is actually a great NAS trick. What it doesAn M.2 NVMe slot (x4) is converted into OCuLink (SFF-8611). Then you can connect: OCuLink → 4-port SATA OCuLink → 8-port SATA OCuLink → U.2 / NVMe backplane BandwidthAn M.2 PCIe 4.0 x4 slot ≈ 8 GB/s Typical SATA drives: ~200 MB/s each So: 4 SATA drives ≈ 800 MB/s 8 SATA drives ≈ 1.6 GB/s ➡ Even an x4 link easily handles 8 drives 5. Example NAS configuration with your boardPossible layout: Motherboard8 SATA drives M.2 slots2 NVMe cache drives or 1 NVMe + 1 OCuLink adapter PCIe x4 slot8-port HBA (LSI card) Realistic drive countsWithout crazy mods: Method Drives Motherboard SATA 8 M.2 NVMe 2 OCuLink adapter 4–8 PCIe HBA card 8–16 Total possible: 20–30 drives 6. Best NAS expansion method (recommended)Instead of Hyper M.2, I strongly recommend: PCIe SAS HBA Examples: LSI 9211‑8i LSI 9300‑8i Advantages: 8–16 SATA drives True enterprise controller Perfect for TrueNAS / Unraid / ZFS 7. What I would do with your exact systemGiven: 2 GPUs USB card Ethernet card I’d do: Onboard 8 SATA drives M.2 slot #1 NVMe cache M.2 slot #2 OCuLink → 4-8 SATA PCIe x4 slot LSI HBA (8 drives) ➡ Total ~20 drives possible 💡 One important NAS tip: Gaming boards like this lack ECC support with some CPUs and IPMI, but performance is excellent. ✅ If you want, tell me: Your CPU model Case size (how many drives physically fit) Which NAS OS (TrueNAS, Unraid, Proxmox) …and I can design an optimal 20-30 drive layout for this motherboard. It’s actually a surprisingly powerful NAS platform. if I do nr 7 i lose the usb card that i pass through to a VM and the same with the ethernet card You’re running into the classic limitation of consumer boards used as NAS/virtualization hosts: not enough PCIe slots once GPUs are involved. Let’s map the ASUS ROG Crosshair VIII Dark Hero slots first so the options are clearer. 1. Your motherboard PCIe slot realitySlots available: PCIe x16_1 (CPU) – normally GPU PCIe x16_2 (CPU) – GPU (runs x8/x8 with slot 1) PCIe x16_3 (chipset) – x4 electrical PCIe x1 So if you're using: GPU #1 GPU #2 USB controller (for VM passthrough) Ethernet card You’ve already filled all usable slots. That means: No slot left for an HBA No slot left for Hyper M.2 So expansion must come from M.2 slots or lane sharing. 2. Best option for your situation: M.2 → SATA/OCuLinkUse the two M.2 slots as your expansion ports. Option A – M.2 → 6-port SATA controllerExample chips: ASM1166 JMB585 Each M.2 adapter can give: 5–6 SATA ports So: Slot Drives M.2_1 adapter 6 SATA M.2_2 adapter 6 SATA Motherboard SATA 8 SATA ➡ Total = ~20 drives No PCIe slots used. 3. M.2 → OCuLink (better than SATA controllers)Instead of SATA controllers, you can convert M.2 to OCuLink. Then connect to: OCuLink → U.2 NVMe OCuLink → SATA backplane OCuLink → SAS HBA Advantages: lower latency higher bandwidth enterprise cabling An M.2 x4 link can comfortably run: 4–8 SATA drives So: Slot Drives M.2 OCuLink 4–8 drives M.2 OCuLink 4–8 drives Motherboard SATA 8 drives ➡ 16–24 drives total 4. Why Hyper M.2 won’t help you muchThe ASUS Hyper M.2 x16 Card V2 requires: a x16 slot PCIe bifurcation But your two x16 slots are already used by GPUs. So it would force you to remove either: GPU Ethernet USB controller Not ideal for your setup. 5. Another trick: USB controller via motherboard headersIf your USB passthrough card is just for extra USB ports, you might not need the card. The ASUS ROG Crosshair VIII Dark Hero already has: multiple USB controllers USB headers Often you can pass through the onboard USB controller to a VM instead of using a card. This frees a PCIe slot. 6. Best layout without losing your cardsPCIe slots GPU 1 GPU 2 USB passthrough card Ethernet card Storage 8 × motherboard SATA M.2 → SATA controller (6 drives) M.2 → SATA controller (6 drives) ➡ 20 drives 7. Ultimate trick (if you want crazy expansion)You can use a PCIe bifurcation riser: x16 → 4 × x4 slots Then one slot can hold: USB card Ethernet SAS HBA etc. But it requires BIOS bifurcation and physical space. 💡 One more important question that changes everything: What CPU are you running? Example: AMD Ryzen 9 5950X AMD Ryzen 7 5800X Because Ryzen CPUs only provide 24 PCIe lanes, and how those lanes are used determines the best expansion strategy. If you want, I can also show you a very clever NAS trick using one M.2 slot that gives 20+ drives while keeping all your PCIe cards. Most homelab builders with this board don’t realize it’s possible. i'm using a 3900x cpu. show me the nas trick with one m.2 With the AMD Ryzen 9 3900X and the ASUS ROG Crosshair VIII Dark Hero, you actually have a very powerful trick available: turn one M.2 slot into a full SAS storage controller without using a PCIe slot. This works because an M.2 NVMe slot is just PCIe x4 lanes. If you convert that slot to a PCIe slot, you can run an HBA exactly like a normal server. The “1× M.2 → 16+ drives” NAS trickStep 1 — Use an M.2 → PCIe x4 adapterThis adapter plugs into the motherboard M.2 slot and gives you a PCIe x4 slot on a cable or riser. What it does: M.2 slot (PCIe 4.0 x4) ↓ PCIe x4 slot Now you can install a real SAS HBA. Step 2 — Install a SAS HBATypical cards: LSI 9211-8i SAS HBA LSI 9300-8i SAS HBA These provide: 8 SATA/SAS drives directly But the real magic comes next. Step 3 — Add a SAS expanderA SAS expander multiplies ports. Example: Intel RES2SV240 SAS Expander Connection: M.2 slot ↓ M.2 → PCIe adapter ↓ LSI 8-port HBA ↓ SAS Expander ↓ 16–24 SATA drives Now a single M.2 slot can run 24 drives. Why this works wellBandwidth calculation: M.2 slot (PCIe 4.0 x4): ~8 GB/s Typical HDD: 150–250 MB/s Even 20 drives only need ~4 GB/s, so the link is still not saturated. So performance is perfect for NAS workloads. Your full system layoutWith your current hardware: PCIe slotsGPU #1 GPU #2 USB passthrough card Ethernet card (no changes required) StorageMotherboard: 8 SATA drives M.2 slot #1: NVMe cache drive M.2 slot #2: M.2 → PCIe adapter → HBA → SAS expander Result: Source Drives Motherboard SATA 8 HBA via M.2 16–24 NVMe cache 1 ➡ 24–32 total drives possible Why homelab NAS builders love this trickIt solves the biggest problem with consumer boards: no PCIe slots left Yet still gives enterprise-style storage expansion. It’s commonly used in TrueNAS, Unraid, and Proxmox builds. One more trick (specific to your board)The ASUS ROG Crosshair VIII Dark Hero has two M.2 slots. If you really wanted extreme storage: M.2 #1 → HBA (24 drives) M.2 #2 → NVMe cache or M.2 #1 → HBA M.2 #2 → second HBA That could theoretically run 40–48 drives from a gaming motherboard. ✅ If you'd like, I can also show you: The exact $15 adapter that works best for M.2 → PCIe How to power the SAS expander without a server motherboard How some people run 30+ drives on this exact board Those tricks make a huge difference for NAS builds. → HBA → SAS expander. how does a sas expander connect with a HBA A SAS expander works a bit like a network switch for storage. Instead of each drive connecting directly to the HBA, the expander lets many drives share a few SAS links from the HBA. Let’s walk through how it connects. 1. Basic connection layoutExample hardware: LSI 9211-8i SAS HBA Intel RES2SV240 SAS Expander Connection looks like this: CPU / Motherboard │ M.2 → PCIe adapter │ LSI HBA │ (SFF-8087 cable) │ SAS Expander ├── Drive 1 ├── Drive 2 ├── Drive 3 ├── Drive ... └── Drive 24 2. The actual cables usedMost SAS HBAs use Mini-SAS connectors. Typical ports on the LSI 9211-8i SAS HBA: 2 × SFF-8087 internal SAS ports Each port carries 4 SAS lanes. So one cable provides 4 drive channels. HBA → Expander cableYou connect them using: SFF-8087 → SFF-8087 cable HBA port │ SFF-8087 cable │ Expander port This creates an uplink from the HBA to the expander. 3. Connecting drives to the expanderThe expander has many ports. Example Intel RES2SV240 SAS Expander: 24 SAS lanes total multiple SFF-8087 ports Each port can break out to 4 SATA drives using a breakout cable: SFF-8087 → 4× SATA Expander port │ Breakout cable ├── SATA drive ├── SATA drive ├── SATA drive └── SATA drive 4. Bandwidth explanationOne SAS lane (SAS2): 6 Gbps One SFF-8087 port: 4 lanes 24 Gbps total If you connect two HBA ports to the expander: HBA port 1 ─┐ ├── Expander HBA port 2 ─┘ You now have: 48 Gbps uplink bandwidth That easily supports 20+ HDDs. 5. Powering the SAS expanderThe Intel RES2SV240 SAS Expander can be powered two ways: Option A (server style)Plug it into a PCIe slot (for power only). Option B (better for your case)Use a Molex power connector. So it can sit anywhere in your case. 6. Why this setup is popular for NASAdvantages: One controller manages dozens of drives Works perfectly with TrueNAS / ZFS Very reliable enterprise hardware Uses very few PCIe lanes 7. Example setup for your systemYour system could look like: M.2 slot ↓ M.2 → PCIe adapter ↓ LSI 9211-8i ↓ Intel SAS expander ↓ 24 HDDs Plus: 8 motherboard SATA drives ➡ 32 total drives possible 💡 Important tip: Flash the LSI 9211-8i SAS HBA to IT mode so it acts as a pure HBA (no RAID). That’s required for TrueNAS, Unraid, and ZFS. If you want, I can also show you something even more interesting: A cheap 36-drive SAS expander setup that uses only one cable from the HBA. Most homelab NAS builders miss that trick, and it works perfectly with your 3900X system.

i've been struggling to get a network connection to my vm's for weeks now. I installed a dedicate LAN card to each VM hahaha. thank you so much