Intel Core Ultra 200S processors cannot light all four drives on a passive quad M.2 card. Intel ARK lists the CPU lane splits as 1×16+2×4, 2×8+2×4 or 1×8+4×4, which leaves the x16 slot at x16, x8+x8 or x8+x4+x4, so the fourth socket stays dark, and the ASUS bifurcation table lists every Z890 board it covers at three drives. The same card in an AM5 board with a Ryzen 9000 or 7000 shows all four drives at 7.88 GB/s each on PCIe 4.0 (Amazon prices checked October 2026).
That split decides which PCIe bifurcation card fits a Proxmox or TrueNAS box: a passive card where the slot splits four ways, a PCIe switch card where it does not. We compared ten quad cards, plus the two-drive and riser options, against maker datasheets and platform tables. Nothing was tested in our lab, so power and bandwidth figures are maker numbers or line-rate arithmetic.
Quad NVMe cards by bandwidth per drive
Bandwidth per drive with all four drives busy is the number that separates these cards. A passive card gives every drive its own x4 link to the CPU, while a switch card shares its uplink among four drives. Passive cards are listed first, then switch cards, each by bandwidth. Per-drive figures use the PCIe line rate after 128b/130b encoding: 0.985 GB/s per lane on Gen3, 1.969 on Gen4 and 3.938 on Gen5.
| Card | Price | Type | Uplink | Per drive, 4 busy |
|---|---|---|---|---|
| ASUS Hyper M.2 x16 Gen5 | about $85 | passive | Gen5 x16 | 15.75 GB/s |
| GLOTRENDS Quad M.2 PCIe 5.0 | about $80 | passive | Gen5 x16 | 15.75 GB/s |
| GLOTRENDS PA41 | about $33 | passive | Gen4 x16 | 7.88 GB/s |
| ASUS Hyper M.2 x16 Gen 4 | about $75 | passive | Gen4 x16 | 7.88 GB/s |
| Sabrent EC-P4BF | about $85 | passive | Gen4 x16 | 7.88 GB/s |
| HighPoint Rocket 1604A | about $999 | switch, PEX89048 | Gen5 x16 | 15.75 GB/s |
| GLOTRENDS PA44 | about $230 | switch, IX8024 | Gen4 x8 | 3.94 GB/s |
| Linkreal PLX8747 x16 | about $126 | switch, PEX 8747 | Gen3 x16 | 3.94 GB/s |
| HighPoint Rocket 1104 | about $249 | switch | Gen3 x16 | 3.94 GB/s |
| GLOTRENDS PA40 | about $160 | switch, ASM2824 | Gen3 x8 | 1.97 GB/s |
Passive cards cost about $1 to $3 per GB/s of uplink; the switch cards here cost about $8 to $20. For a NAS, even the slowest row is enough: 1.97 GB/s per drive still outruns a 10GbE link at 1.25 GB/s, and the shared 7.88 GB/s of a Gen3 x8 switch card outruns 25GbE at 3.125 GB/s. The uplink only limits local work such as a scrub, a resilver or VM disks on the host itself.
How the cards and platforms were checked
Two kinds of evidence drive the ranking, the card datasheet and the platform table, and the second one decides more purchases than the first:
- Card specs: maker datasheets and product pages for ASUS, GLOTRENDS, Sabrent, HighPoint and StarTech, plus Amazon listing text where no maker page exists.
- Platform splits: the ASUS bifurcation tables per chipset and CPU, Intel ARK for Core Ultra 200S, and board spec sheets.
- Listings: the Amazon Creators API plus a page read from a New York address for seller, stock and price.
- No lab testing: no card was installed, so throughput is line-rate arithmetic and power is the maker figure.
One wording trap runs through the GLOTRENDS pages. “Not Support PCIe Bifurcation” on the PA41 means the card has no switch and the board must bifurcate, while “Support PCIe Bifurcation” on the PA40 and PA44 means the card has a switch chip. This guide uses “needs bifurcation” and “has a switch chip” instead.
Step 1: Find out what your x16 slot can split
A passive quad card needs the slot set to x4x4x4x4, and the CPU decides whether that mode exists. The ASUS tables and Intel ARK give these results for the platforms homelab builders use most:
| Platform and CPU | Drives a passive quad card shows | Source |
|---|---|---|
| AM5 X870E or B850, Ryzen 9000/7000 | 4 on the first CPU x16 slot | ASUS tables |
| AM5 X870E or B850, Phoenix-based Ryzen 8000 (8000G and F parts) | 1 | ASUS tables |
| LGA1851 Z890, Core Ultra 200S | 3 (x8+x4+x4) | ASUS tables, Intel ARK |
| TRX50, Threadripper 7000 | 4 on slots 1 and 2, 2 on slot 3 | ASUS Pro WS TRX50-SAGE |
| WRX90, Threadripper PRO 7000 WX | 4 on six of seven slots | ASUS Pro WS WRX90E-SAGE SE |
| W790, Xeon W-3400 | 4 on most slots | ASUS Pro WS W790E-SAGE SE |
| W790, Xeon W-2400 | slots 2, 4 and 6 not supported | ASUS Pro WS W790E-SAGE SE |
Two smaller traps sit inside the AM5 rows. The Phoenix-based Ryzen 8000 chips give the x16 slot fewer lanes, so a quad card shows one drive. On the ProArt X870E-Creator, populating the M.2_2 socket drops the first x16 slot to x8, which halves a quad card to two drives, and on several X870E boards populating the second x16 slot does the same. The multi-GPU motherboard guide covers how each board shares those lanes.
Used workstation towers are less predictable. The Lenovo P520 added x16 bifurcation in a BIOS update, owners report that the Dell Precision 5820, 7820 and 7920 have no menu but configure the slot automatically, and HP does not document it, as our used workstation guide explains. The PCIe lanes guide covers how CPU and chipset lanes are counted.
Step 2: Pick a passive card when the slot splits x4x4x4x4
If Step 1 says four drives, a passive card is the right answer: full bandwidth per drive, no switch power and a lower price. These four are the passive cards worth buying, ordered by generation.
ASUS Hyper M.2 x16 Gen5
For a Gen5 slot on AM5 or Threadripper, the ASUS Gen5 card is the passive pick with the best cooling. It is also the only one with dedicated drive power.
ASUS fits four M.2 drives from 2242 to 22110 on a PCIe 5.0 x16 card, with an active blower fan, a heatsink and thermal pads on both sides. ASUS adds one 6-pin PCIe power connector and a two-phase supply rated up to 14 W per drive, about 56 W for four, well past the 25 W a non-graphics x16 card may draw at power-up under the PCIe CEM spec. ASUS powers the drives through that 6-pin lead, so connect it and plan a spare PSU cable.
On our check date Amazon itself sold it for about $85 with stock on hand. At 29 cm long it needs a full-length slot clear of other cards.
GLOTRENDS PA41
For four Gen4 drives in a slot that splits four ways, the PA41 is the cheapest route. It is also the simplest card here, with no fan and no power lead to connect.
GLOTRENDS built it for 2230 to 22110 drives on a PCIe 4.0 x16 card with no switch chip, and the maker states the rules plainly: x4x4x4x4 shows four drives, x8x4x4 shows three, and without bifurcation only the first socket works. Both low-profile and full-height brackets are in the box. There is no fan, so it depends on case airflow.
Expect about $33 from the GLOTRENDS store, under half the price of any other passive card here. The same seller’s Gen5 quad card at about $80 has no fan and no power connector, so check drive temperatures under load before trusting four Gen5 drives on it.
ASUS Hyper M.2 x16 Gen 4
ASUS sells the named-brand alternative to the PA41, with a fan and a long review history. It costs more for the same Gen4 bandwidth.
Four 2242 to 22110 drives fit on it, it runs in x8 and x16 slots, and carries a fan with a switch and four status LEDs. In an x8 slot that splits x4x4 it shows two drives, and in an x8 slot that does not split it shows one, since the card has no switch. The Amazon-sold listing had no buy box on our check date, so the offer came from a reseller.
Neutron USA sold it for about $75 with several hundred ratings. That is more than twice the PA41 for the same Gen4 bandwidth, so buy it for the fan and the ASUS support pages.
Sabrent EC-P4BF
Sabrent makes the quiet passive option, with a fan you can switch off. It also drops 22110 support, which matters only for some enterprise drives.
Four 2230 to 2280 drives sit behind an aluminium cover with thermal pads and an optional fan on a rear switch. Sabrent states x4x4x4x4 for three or four drives and x8x8 or x4x4 for two. Leave the fan on if the case has weak airflow across the slot.
Store4PC sold it for about $85. Sabrent also lists an EC-P3X4 card for four drives on an x4 slot. Its maker page lists ASM2824-style power features while the Amazon listing says it has no onboard switch, so we left it out.
Step 3: Use a PCIe switch card when the slot cannot split
On Z890, on a Phoenix-based Ryzen 8000, or in a tower whose slot will not split, a switch card is the only way to see four drives in one slot. The switch chip presents one device to the slot and fans the lanes out to four drives, at the cost of a shared uplink, a few watts and a small latency:
| Factor | Passive card | Switch card |
|---|---|---|
| Slot requirement | x4x4x4x4 in the BIOS | any x8 or x16 slot |
| Bandwidth | full x4 per drive | uplink shared by four drives |
| Latency | none added | PEX 8747: 100 ns maximum |
| Power | no card logic | PEX 8747: 8.0 W typical |
| Proxmox passthrough | one root port per drive | ACS only to split drives between VMs |
Passthrough matters if a TrueNAS VM will own the drives. Proxmox needs a dedicated IOMMU group for the devices you assign to a VM, so drives behind a switch without ACS can only be passed together. That is fine when one VM owns all four, but splitting them between VMs or keeping one for the host needs ACS. Broadcom lists ACS for the PEX 8747, while the ASM2824 and IX8024 pages do not mention it. The Proxmox PCI passthrough page covers IOMMU groups.
GLOTRENDS PA40 (ASM2824)
GLOTRENDS sells the budget switch card in the PA40, and it runs in any x8 or x16 slot. It is the cheapest way past a slot that cannot split.
An ASMedia ASM2824 switch takes a PCIe 3.0 x8 uplink and serves four 2230 to 22110 drives, which GLOTRENDS states as four drives sharing about 8 GB/s. ASMedia lists L0s, L1 and L1 substates, LTR and AER for the chip, but no ACS. A heatsink fan cools the switch.
Expect about $160 from GLOTRENDS. At 1.97 GB/s per drive with all four busy, it suits a NAS behind a 10GbE or 25GbE link, not a local database.
GLOTRENDS PA44 (IX8024)
With a PCIe 4.0 switch, the PA44 doubles the per-drive bandwidth of the PA40. The trade is a chip with almost no public documentation.
GLOTRENDS uses an IX8024 switch on a PCIe 4.0 x8 uplink, for 3.94 GB/s per drive when all four are busy, and takes 2280 drives only. The chip has no English datasheet we could find, so its power draw, ACS support and Linux behaviour are undocumented. Treat it as the newer, less proven option.
GLOTRENDS sold it for about $230. The Linkreal PLX8747 card at about $126 gives the same 3.94 GB/s per drive on a Gen3 x16 uplink with a documented Broadcom chip, but its specs come from the Amazon listing alone.
HighPoint Rocket 1604A
For Gen5 drives on a board that cannot bifurcate, the Rocket 1604A is the only full-bandwidth switch card here. Its price reflects that.
A Broadcom PEX89048 switch gives it 16 lanes to the slot and a dedicated Gen5 x4 link per M.2 port. HighPoint lists no external power connector, a heatsink with a fan, 2242 to 2280 drives and a working range of 5 to 55 °C. It is a plain switch card, not the RAID version, which matters for ZFS. HighPoint lists a synthetic hierarchy and its own management driver, so the lspci tree in Step 5 may look different on this card.
HighPoint sold it for about $999 with one left, more than ten times the ASUS Gen5 card. HighPoint’s Gen3 Rocket 1104 at about $249 is the cheaper fanless switch card, rated at 7.74 W typical.
Step 4: Put two drives in an x8 slot
A second x8 slot, an x8 slot on a mini PC, or a board that splits x8x8 is enough for two drives. The GLOTRENDS PA21 at about $27 is the cheapest passive option, but GLOTRENDS says it does not work in x8x4x4 mode, and most Z890 boards have no slot that gives x4x4, so it shows one drive there. These two StarTech cards cover the passive and switch routes.
StarTech DUAL-M2-PCIE-CARD-B
StarTech makes the passive two-drive card for a slot that splits x4x4. It is the Amazon-sold option in this group.
Two 2242 to 22110 drives fit on PCIe 4.0 x8 and fits x8 or x16 slots, and StarTech states that bifurcation is required. StarTech rates it for -40 to 80 °C. At 22.8 cm long it needs a tower or desktop case with room for a 23 cm card, so it will not fit a mini PC such as the MS-A2 in our mini PC comparison.
Expect about $72 from Amazon itself, with limited stock. It is more than twice the price of the PA21, so buy it for the StarTech name and support.
StarTech PEX8M2E2
For two drives in a slot that cannot split, StarTech offers the PEX8M2E2. Its switch chip handles the split itself.
An ASMedia ASM2824 on a PCIe 3.0 x8 uplink serves two 2242 to 2280 drives, and StarTech states that bifurcation is not required. With two drives sharing x8, each gets about 3.94 GB/s when both are busy. Low-profile and full-height brackets are included.
Amazon listed it at about $167. Like the PA40, its switch chip does not list ACS, so test passthrough before you plan to hand the drives to a VM.
Step 5: Set bifurcation and confirm every drive in Linux
Update the BIOS first, because bifurcation support often arrives in a BIOS release, as it did on the Lenovo P520. Menu names vary by maker, so look for the slot by name and a setting such as PCIe bifurcation, x4x4x4x4 or Hyper M.2 x16, and set it on the exact slot that holds the card. Then boot Proxmox VE or TrueNAS SCALE and check the topology. The Proxmox shell runs as root, so the commands below have no sudo; on TrueNAS SCALE, run them as root or prefix them with sudo:
lspci -tvOn a bifurcated card each drive appears behind its own root port. On a switch card the drives sit behind one root port, then the switch upstream port and one downstream port per drive. Proxmox does not install nvme-cli by default, so refresh the package lists and add it before you count the drives. TrueNAS SCALE disables apt, so skip this step there:
apt update && apt install nvme-cliThen list the drives the kernel created:
nvme listFour drives should give four /dev/nvme entries; three on a Z890 board is the x8x4x4 limit from Step 1. To confirm each drive negotiated the expected speed and width, find the PCI address of each NVMe controller first:
lspci -D | grep -i 'non-volatile'Then read the link status for one drive, replacing 0000:01:00.0 with an address from that list:
lspci -vv -s 0000:01:00.0 | grep -E 'LnkCap|LnkSta'LnkCap shows what the drive supports and LnkSta what it negotiated. A drive at Gen3 behind a Gen4 card, or x2 instead of x4, points at a riser, a slot setting or signal quality. Our NVMe for Proxmox guide covers which drives to put on the card.
Step 6: Lay out the ZFS pool across cards and root ports
A single card is a single point of failure, so place mirror halves on different cards or on the card and an onboard M.2 socket. Losing one card then degrades each mirror instead of taking the pool down. A RAIDZ vdev on one card has no such protection.
Avoid hardware RAID cards for this job. Proxmox says not to run ZFS on a hardware RAID controller with its own cache management, and TrueNAS says not to use a card’s RAID feature when an HBA mode exists. For that reason we left out RAID cards such as the HighPoint Rocket 7604A and SSD7505. Build the pool from /dev/disk/by-id/ paths so drive order does not matter after a reboot, and keep ashift=12 for 4K-sector NVMe drives. Our TrueNAS ZFS build and SLOG and special vdev guide cover the rest of the layout.
Step 7: Add a riser without losing link speed
Risers are where storage cards lose link speed, and the maker statements show how little is guaranteed for storage. These are the ones to read before you buy:
- ADT-Link M14V4: the maker says it does not guarantee full PCIe 4.0 speed and advises dropping to PCIe 3.0 if errors appear.
- Corsair: its PCIe 5.0 riser is designed for GPU vertical mounting, and M.2 adapter cards are not guaranteed.
- Length: ADT-Link counts only the visible wire, not the PCB and connectors.
- x1 risers: an x1 to x16 extension such as the StarTech PEX1TO162 carries one lane, under 1 GB/s even at Gen3, and StarTech lists this one at 2.5 Gbps.
If a riser is unavoidable, pick one rated for the slot generation and check LnkSta after install. LINKUP claims full Gen5 bandwidth on its PCIe 5.0 riser at about $63, tested with a GPU. For a bifurcated x8x8 split, about $110 buys the RGEEK x16 to x8x8 riser, and about $89 buys the GLOTRENDS Gen5 x8/x8 splitter cable. Both need the BIOS set to x8x8. An ADT-Link M.2 to PCIe x4 riser at about $33 turns a spare M.2 socket into a Gen4 x4 slot.
Thermaltake TT Premium PCI-E 4.0 riser
For a Gen4 card on a riser, the Thermaltake cable is the Amazon-sold option with shielding. It is also the longest cable here.
Thermaltake specifies EMI shielding with a conducting polymer and five flat cables, and rates it for PCIe 2.0, 3.0 and 4.0. At 300 mm it is long for storage traffic, so check LnkSta on every drive after you route it. Amazon itself listed it at about $100.
Drop the slot to Gen3 in the BIOS if correctable errors appear. A Gen4 x4 drive at Gen3 still gives 3.94 GB/s, enough for most NAS work. Our local AI workstation build uses a riser for the GPU, which is the job these cables are designed for.
Corsair Premium PCIe 5.0 riser
Corsair sells the Amazon-stocked Gen5 riser, with a caveat printed in its own guide. Read that caveat before you buy it for storage.
Corsair says it complies with the PCIe 5.0 specification at 32 GT/s, and at 175 mm it is one of the shorter Gen5 risers. Corsair’s quick start guide also says it is designed for GPU vertical mounting and that M.2 adapter cards are not guaranteed. That makes it a GPU part first.
Amazon sold it for about $100. If you mount an ASUS Gen5 quad card on it, confirm every drive reaches Gen5 in LnkSta before you build a pool on it, and expect to fall back to Gen4.
U.2 drives on a bifurcation card
U.2 follows the same split. The GLOTRENDS PU41 at about $45 is a passive x16 card for four U.2 drives that needs x4x4x4x4, and the HighPoint Rocket 1120 at about $149 is a Gen3 x16 switch card that needs no bifurcation. U.2 drives also need 12 V power at the drive and steady airflow, which M.2 drives on a card do not, so plan the cabling and the fan before you order. Our used U.2 NVMe guide covers the drives, adapters and cooling in detail.
Tuning four drives behind one slot: link speed, ASPM and ashift
Once all four drives appear, four changes decide whether they stay fast and stable. Each one is a single change with a known failure mode:
- Link speed: force the slot one generation lower in the BIOS when LnkSta shows downtraining or the kernel logs AER correctable errors; Gen4 at Gen3 halves per-drive bandwidth but usually clears the errors.
- Power states: if drives drop after idle, try
nvme_core.default_ps_max_latency_us=0to disable NVMe APST, thenpcie_aspm.policy=performance;pcie_aspm=offonly leaves the firmware ASPM setup unchanged, andpcie_aspm=forcecarries a kernel warning about lockups. - ashift: create pools with
ashift=12; it cannot be changed after the vdev exists. - Scrub timing: on a switch card all four drives share the uplink during a scrub or resilver, so schedule scrubs outside backup windows.
None of these settings changes the first table. A passive card on a slot that splits x4x4x4x4 gives each drive up to eight times the bandwidth of a Gen3 switch card at a fraction of the price, and a switch card remains the answer where the platform leaves no choice.
