Six hard drives behind an ASM1166 card share one PCIe 3.0 x2 link of about 1,969 MB/s, or roughly 328 MB/s each when all six read at once. Seagate rates its 24TB IronWolf Pro at 285 MB/s, so the link never holds the drives back. That is why the best SATA card for Unraid or TrueNAS is usually a plain AHCI card, not a SAS HBA. Cheaper silicon breaks the arithmetic: a Marvell 88SE9215 card leaves four drives about 125 MB/s each.
This guide ranks SATA expansion cards by bandwidth per drive and idle behaviour. It covers the ASM1166 and JMB585 AHCI controllers, an M.2 to SATA adapter for mini PCs, and the LSI 9211-8i HBA for builds past six extra disks. Every figure comes from maker datasheets, Unraid and TrueNAS hardware guidance and Linux kernel commits (sources checked in October 2026).
SATA expansion cards ranked by bandwidth per drive
Three cards cover almost every Unraid and TrueNAS build that has run out of onboard SATA ports. We picked them on the per-drive column of the table below, then on firmware support and idle power:
- Best overall, SilverStone ECS06 (ASM1166): six ports on PCIe 3.0 x2, a maker firmware download for Intel 600-series boards, and about 328 MB/s per drive. Check the live price.
- Best for a mini PC, SilverStone ECS07 (JMB585): five ports from a spare M.2 slot, about 394 MB/s per drive. Check the live price.
- Best past six drives, LSI 9211-8i in IT mode: eight ports on PCIe 2.0 x8, about 500 MB/s per drive, at the cost of higher idle power. Check the live price.
Per-drive bandwidth is the PCIe link rate divided by the number of ports, before protocol overhead. It sets the speed of an Unraid parity check or a ZFS scrub, because both read every disk at the same time:
| Card (controller) | Host link | SATA ports | Link rate | Per drive, all ports busy | Price band |
|---|---|---|---|---|---|
| LSI 9211-8i (SAS2008) | PCIe 2.0 x8 | 8 | 4,000 MB/s | 500 MB/s | about $75 |
| SilverStone ECS07 (JMB585) | M.2, PCIe 3.0 x2 | 5 | 1,969 MB/s | 394 MB/s | about $45 to $50 |
| SilverStone ECS06 (ASM1166) | PCIe 3.0 x2 | 6 | 1,969 MB/s | 328 MB/s | about $75 to $80 |
| Generic ASM1166, x1 variant | PCIe 3.0 x1 | 6 | 985 MB/s | 164 MB/s | avoid |
| Marvell 88SE9215 cards | PCIe 2.0 x1 | 4 | 500 MB/s | 125 MB/s | avoid |
| 10-port cards with a port multiplier | one SATA link per multiplier | 5 per multiplier | 600 MB/s | 120 MB/s | avoid |
Read the table against your drives. A 7,200 rpm NAS disk streams 250 to 285 MB/s on its outer tracks. Anything above 285 MB/s per drive never slows a pool of hard drives, and anything below 200 MB/s does. All three picks clear that line. The three rows marked avoid fall short by a factor of 1.7 to 2.4, which roughly doubles the length of every parity check and scrub.
Where the numbers come from
The ranking rests on published sources, and each one is named where its number appears:
- Controller specs: the SilverStone ECS06 and ECS07 spec pages, the JMicron product list for the JMB585 and JMB575, and the Marvell 88SE9215 datasheet.
- Platform guidance: the recommended controllers thread on the Unraid forum, and the storage controller section of the TrueNAS hardware guide.
- Linux driver behaviour: the upstream ahci commits that changed how the ASM1166 reports its ports.
- Price and stock: Amazon’s catalog API on the day of writing, so each pick links to a listing that was in stock.
Bandwidth figures are therefore ceilings. A real ASM1166 or JMB585 card loses some of its link rate to PCIe packet overhead. We found no measured aggregate for either chip that we could cite, so the per-drive column ranks the cards rather than predicting what a scrub will report.
Count drives, slots and lanes before you buy
Three numbers from your board manual pick the card: how many drives you need to add, which slot is free, and how many PCIe lanes that slot carries. An x16-length slot wired at x4 is common on consumer boards. It suits every card here except the LSI, which wants x8.
- Up to five extra drives and no free PCIe slot: use a spare M.2 slot with the JMB585 adapter. This is the mini PC and small-board case.
- Up to six extra drives and a free x4 or larger slot: buy an ASM1166 card. In the one idle-power log we could cite, it added the fewest watts of these chips when fitted in a chipset slot.
- Seven or more extra drives, SAS disks, or a backplane with SFF-8087 or SFF-8643 connectors: buy an LSI HBA flashed to IT mode and accept the extra idle watts.
Unraid and TrueNAS agree on the third case. The Unraid forum controller list names the LSI SAS2008, SAS2308 and SAS3008 families in IT mode for eight ports and more. The TrueNAS hardware guide calls the 6 Gbps LSI 9211 “legendary among TrueNAS users”. They differ on the AHCI cards: Unraid lists the ASM1166 and JMB585 as recommended, while the TrueNAS guide (written for CORE 13.0) covers onboard SATA and SAS HBAs and does not mention AHCI add-in cards. ZFS itself does not care, because an AHCI controller passes each disk to the OS the same way onboard SATA does. If you are still choosing the OS, the TrueNAS vs Unraid comparison covers how each one uses the disks.
Best ASM1166 card for six more drives: SilverStone ECS06
We would buy the SilverStone ECS06, and the reason is firmware, not silicon. Cheaper ASM1166 cards are easy to find, such as the GLOTRENDS SA3026C at about $37 in October 2026. SilverStone publishes a firmware update on its own product page, and the cheaper listings we checked link to none. That matters because ASM1064 and ASM1166 cards with older firmware are not detected on some Intel 600-series boards.
SilverStone’s ECS06 spec page lists a PCIe Gen3 x2 host interface, six SATA 6Gb/s ports, AHCI 1.4 and device sleep. It also lists command-based port-multiplier switching, on a low-profile board 112.2 mm long. The card in the SilverStone product render has an x4-length edge, so plan on an x4, x8 or x16 slot, of which it uses two lanes. An open-ended x1 slot also takes it, at half the bandwidth. At 328 MB/s per drive it keeps six hard drives at full speed through a parity check. Six SATA SSDs would run at about 60% of their rated 550 MB/s.
In idle measurements from one user the ASM1166 cost almost nothing, with one condition: where it sits. A user log on the Hardwareluxx lowest-idle thread measured an ASM1166 on a chipset x4 slot at 1 W above the bare board, with the package still reaching C8. In a CPU-attached x16 slot the same card cost 14 W, and the package stopped at C2. That is one board, not a rule. It still says to try the chipset slot first and check the package C-state with powertop before you close the case.
Who it suits: an always-on Unraid or TrueNAS box with four to six drives on the card and a free x4 slot. Skip it if you need more than six extra ports, or plan an all-SSD pool where 328 MB/s per drive wastes the SSDs. Price runs about $75 to $80; check the live price on Amazon.
Best M.2 to SATA adapter for mini PCs: SilverStone ECS07
A mini PC or a small ITX board usually has a spare M.2 socket and no PCIe slot at all. The SilverStone ECS07 turns that socket into five SATA ports. It is the cheapest route to a five-disk array on the kind of hardware in our mini PC NAS build.
According to the ECS07 spec page, the card carries a JMicron JMB585 on an M.2 PCIe Gen3 x2 interface, with five SATA ports, device sleep and an aluminium heatsink. It is 80.5 mm long, the 2280 size, so the socket must take a full-length M.2 drive. It must also be an NVMe (PCIe) socket, because a SATA-only M.2 slot will not run it. Five ports on the same x2 link give 394 MB/s per drive, the best figure of the AHCI cards here.
Its trade-offs are physical and electrical. The SilverStone render shows the SATA connectors standing up from the board, so the cables need clearance above the M.2 slot, and in a closed mini PC they need a way out of the case. JMicron also lists FIS-based port-multiplier support for the JMB585, the feature behind the 10 and 20-port cards covered below; on a five-port card it does nothing. In the same Hardwareluxx log a JMB585 card (model not stated) added 4 to 7 W over the 8 W baseline and held the package at C3 in both slot types. The same poster advised running these controllers as PCIe cards rather than on an M.2 adapter, because the M.2 route blocked deeper C-states. A low-power build that has a PCIe slot should take the ECS06 instead.
Who it suits: mini PCs and ITX boards with a free NVMe socket and up to five disks. Skip it if you have a free PCIe slot, or the case has no route for five SATA cables. Price runs about $45 to $50; check the live price.
LSI 9211-8i HBA for more than six drives
An eight-port SAS HBA beats two AHCI cards once the build needs seven or more extra drives. Of those HBAs, the LSI 9211-8i is the cheapest that both Unraid and TrueNAS name. It is also the only card here that drives SAS disks and connects to a backplane with one cable per four bays.
Its SAS2008 controller carries eight 6Gb/s ports on a PCIe 2.0 x8 card, split over two SFF-8087 connectors that each fan out to four drives. PCIe 2.0 x8 gives 4,000 MB/s, or 500 MB/s per drive with all eight busy. That is enough for eight SATA SSDs at close to their rated speed. In IT mode the card passes every disk through raw, which is the firmware the TrueNAS guide tells you to flash. The listing we link is a reseller card already flashed to P20 IT firmware. The 9211-8i is a long-discontinued design, so every card on sale is reseller stock covered only by the reseller warranty, and counterfeits of this family circulate.
What you pay is power and heat. An HBA runs its own processor and needs airflow across the heatsink. The Unraid controller thread even names the Syba 16-port card, built from four ASM1064 chips, as a lower power and heat option than an LSI HBA. The 9211-8i also needs an x8 slot, which many consumer boards only offer by splitting the GPU slot. In an x4-wired slot it runs at 2,000 MB/s, or 250 MB/s per drive with all eight busy. For SAS3 cards, cabling, counterfeit checks and 16-port options, see our HBA card guide for TrueNAS.
Who it suits: builds adding seven or more drives, SAS disks, or a case with a backplane. Skip it if the box idles 24 hours a day and six ports would do. Price runs about $75; check the live price.
Marvell x1 and port-multiplier cards to avoid
Three kinds of card fill the “SATA expansion card” search results, and all three fail the per-drive test. The Unraid controller thread puts it in one line: “Avoid SATA port multipliers with Unraid, also avoid any Marvell controller.”
- Marvell 88SE9215 cards: the Marvell datasheet describes the chip as “One-Lane PCIe 2.0 to Four-Port 6 Gbps SATA”. One lane at 500 MB/s across four drives is 125 MB/s each, under half of what a current NAS drive streams.
- ASM1166 cards with an x1 edge: the Unraid thread notes the chip also ships on x1 cards, and Amazon lists at least one “PCIe 3.0 x1 to 6-Port” ASM1166 card. Half the lanes means 164 MB/s per drive. That is fine for two or three slow disks and a bottleneck for six NAS drives. Check the edge connector in the photos before you order.
- 10 and 20-port cards built on one ASM1166 or JMB585: an ASM1166 has six ports and a JMB585 has five. A card that advertises more on one of those chips adds port multipliers such as the JMicron JMB575, which turns one SATA port into five. All five drives behind it share one 600 MB/s link, 120 MB/s each, and a multiplier fault drops all five at once. Cards with several controller chips, such as the four-chip Syba 16-port card named in the LSI section, are a different design with no multiplier.
Port-multiplier cards cost the most to learn about. They pass a quick copy test and only show the problem under a parity check or a scrub, when every disk on them reads at once. If a listing says 10 ports and names a single ASM1166, it has a multiplier, whatever the title says about speed.
Troubleshooting ASM1166 and JMB585 cards
Two of the problems below come from the ASM1166 itself and are documented in the kernel history and the WinRAID thread. The third is about the slot and the disks.
“32 slots 32 ports 6 Gbps 0xffffff3f impl SATA mode”
Linux commit ahci: asm1166: correct count of reported ports quotes this kernel line. It says the chip “always reports wrongly, that it has 32 ports. But in reality, it only has six”. The driver then probes 26 phantom ports at boot, which adds a delay. The fix, merged in January 2024, limited the port map to six. A March 2024 commit reverted it, because the extra ports are how the chip addresses drives behind a port multiplier. A later commit gave the ahci driver a mask_port_map module parameter for anyone who wants the delay gone. On Unraid and TrueNAS the slower boot is cosmetic, and the six real ports work either way.
ASM1166 card not detected on an Intel 600-series board
An ASM1064 or ASM1166 card missing from lspci on a B660, H670 or Z690 board is the firmware incompatibility tracked in the WinRAID ASMedia firmware thread. SilverStone publishes “ECS06 firmware for Intel 600series chipset” (build 211108) on the ECS06 page. That download is the main reason to pay its premium over a generic card. The Unraid controller thread adds that some ASM1166 cards need a firmware update for stability or for PCIe ASPM support.
Parity check or scrub runs at half the expected speed
Slot wiring is the usual cause. A card in a slot wired at x1, or one that runs at PCIe 2.0 speed, gets half the link rate in the table, and the board manual shows how each slot is wired. If the slot is right, look at the slowest disk. A parity check runs at the pace of the slowest drive in the array, so one SMR disk or one tired drive drags the whole run. Our CMR vs SMR breakdown shows how to tell the two apart. The NAS hard drive picks list CMR models that hold their rated speed behind any of the three cards above.
