A two-machine 100GbE link costs $837.97 today - two QSFP28 cards and one QSFP28 DAC, no switch. A switched four-host setup runs $3026.92 ($756.73/host). Breaking one 100G port to four 25G hosts instead costs $1163.84 total ($290.96/host, origin card shared) - usually the cheaper path per host.
Prices updated · 26 100GbE-speed listings tracked
A 100GbE port is rarely bought to feed one machine at the full rate - it is four 25G lanes in one connector, and a breakout cable is the standard, documented way to split them into four independent 25G links. Computed live: one Intel E810 (QSFP28) as the origin, one QSFP28-to-4x25G breakout DAC, and 4 × Intel E810 (SFP28) - one per host - comes to $1163.84 total, $290.96 per host not counting the shared origin card.
ipolex ipolex QSFP28 card (Intel E810 claimed) $405.99 · 10Gtek breakout DAC $45.89 · H!Fiber H!Fiber SFP28 card (Intel E810 claimed) $177.99 each
| Card | Ports | Interface | Condition | Price | |
|---|---|---|---|---|---|
| Intel E810 ipolexseller claims this chipset | 2 | QSFP28 | New | $405.99 | Buy |
| Intel E810 10Gtekseller claims this chipset | 2 | QSFP28 | New | $479.99 | Buy |
| ConnectX-5 Mellanox | 1 | QSFP28 | New | $485.00 | Buy |
| ConnectX-5 Mellanox | 2 | QSFP28 | Refurb | $489.99 | Buy |
| ConnectX-5 Mellanox | 1 | QSFP28 | New | $679.00 | Buy |
| ConnectX-5 Mellanox | 2 | QSFP28 | New | $750.00 | Buy |
Straight point-to-point (no breakout): the cheapest Intel E810 card is $405.99chipset attribution is the seller's; two of those plus the cheapest QSFP28 DAC ($25.99, 0.5m) comes to $837.97 for one full-rate link between two machines.
Passive direct-attach copper, by length. A DAC is a fixed-length cable with the transceivers moulded on - you buy the whole run at once rather than a cable plus two modules.
| Length | Brand | Type | Price | |
|---|---|---|---|---|
| 0.5m | 10Gtek | QSFP28 passive | $25.99 | Buy |
| 1m | 10Gtek | QSFP28 passive | $27.99 | Buy |
| 1m | 10Gtek | QSFP28 passive | $27.99 | Buy |
| 1m | 10Gtek | QSFP28 passive | $45.99 | Buy |
| 2m | 10Gtek1 seller compat claim | QSFP28 passive | $33.99 | Buy |
| 2m | 10Gtek | QSFP28 passive | $45.89 | Buy |
| 2m | ipolex | QSFP28 passive | $48.99 | Buy |
| 2m | 10Gtek | QSFP28 passive | $50.99 | Buy |
| 3m | 10Gtek | QSFP28 passive | $35.09 | Buy |
| 3m | 10Gtek | QSFP28 passive | $35.09 | Buy |
| 3m | 10Gtek | QSFP28 passive | $38.99 | Buy |
| 3m | 10Gtek | QSFP28 passive | $57.99 | Buy |
Every "compatible with" phrase below is the seller's own wording, recorded as a claim and badged. We have not tested any module against any switch.
| Module | Type | Brand | Seller compatibility claims | Price | |
|---|---|---|---|---|---|
| QSFP28 100GBASE-SR4 module | 100GBASE-SR4 | 10Gtek | none stated | $39.99 | Buy |
| QSFP28 100GBASE-SR4 module | 100GBASE-SR4 | 10Gtek | none stated | $39.99 | Buy |
| QSFP28 100GBASE-SR4 module | 100GBASE-SR4 | 10Gtek | none stated | $39.99 | Buy |
| QSFP28 100GBASE-LR4 module | 100GBASE-LR4 | QSFPTEK | for QSFP-100G-LR4-Sseller claim | $229.99 | Buy |
| QSFP28 100GBASE-LR4 module | 100GBASE-LR4 | QSFPTEK | none stated | $269.99 | Buy |
A 100GbE link needs real PCIe bandwidth to the host, and the vendor's own stated requirement - not a throughput number of ours - is what decides whether a slot works. NVIDIA's manuals state ConnectX-5's 100G SKUs at PCIe 3.0 x16, with the ConnectX-5 Ex variant adding PCIe 4.0 x16 on its 100G SKUs. Intel's PCIe figure for E810's 100G SKU was not sourced in our research pass - ark.intel.com did not render for us this session - so that card's own page states the gap rather than assuming a figure from the family pattern. Either way: check the exact part number's own PCIe line, and check your slot's electrical width rather than its physical size, before buying a 100G card.
| Switch | Ports (as listed) | Price | Condition | |
|---|---|---|---|---|
| QNAP QSW-M7308R-4X-US | QSW-M7308R-4X-US, 4x 100GbE QSFP28 + 8x 25GbE SFP28 | $1299.00 | New | Buy |
| Dell S5248F-ON | S5248F-ON, 48x 25GbE SFP28 + 4x 100GbE QSFP28 | $2599.90 | Refurb | Buy |
| Mellanox Spectrum-based Open Ethernet Switch (exact model not stated) | 10/25GbE and 100GbE 1U Open Ethernet switch | $4995.00 | Refurb | Buy |
| Mellanox MSN2100-BB2F Spectrum SN2100 | SN2100, 16x 40 Gigabit QSFP28, L3 managed | $5849.00 | Refurb | Buy |
None of the switches in this table had a vendor datasheet render with a power or acoustic figure in our sourcing pass - NVIDIA/Mellanox's per-model SN2000-series PDFs downloaded but did not extract to legible text, and Dell's and QNAP's datasheets were not part of this pass. Stated as a sourcing gap rather than papered over with an estimate; what is fair to say without a figure: every unit here is 1U rack-mount datacenter hardware built for a cooled server room, not a desk.
Very few home or homelab builds have one machine that genuinely needs a full 100Gb/s link to another single machine - the far more common shape is one fast uplink feeding several 25G hosts, which is exactly what a QSFP28-to-4x25G breakout cable does, per the standard rather than as a workaround.
That reframes the buying decision: a single 100G card and a breakout cable can be cheaper per connected host than four separate 25G point-to-point links would be, because the origin card and the switch port (where one exists) are shared costs. The fanout arithmetic above is computed from exactly that shape, live.
The trade is topology, not cost: a breakout cable's four legs are four independent links from one port, not one device getting four times the bandwidth. Where a build genuinely needs one very fast link rather than several independent ones, a straight QSFP28 DAC or optic is the simpler, more standard answer.
The 25/40/100GbE hub has the full cluster and the form-factor map · 40GbE is the tier below this one, and often the cheapest switched build of the three · ConnectX-5 and Intel E810 are the two cards this page's live builds use · the cabling guide covers breakout cabling in full · rack disk shelves and NAS devices are the usual hardware on the other end - this page prices the link, not what your storage can do with it.
This page prices the link and states what vendors document; whether your storage or workload can use it is a question we don't answer here - see /enclosures/jbod and the NAS pages for the hardware facts on the other end. What we can say: a 100G port is frequently bought to break out to several 25G hosts rather than to feed one machine at the full rate - see the breakout arithmetic below.
Depends on the exact SKU, and this is the category's most expensive mistake to get wrong. NVIDIA's own manuals state ConnectX-5 100G SKUs at PCIe 3.0 x16 (PCIe 4.0 x16 on the Ex variant); Intel's PCIe requirement for E810 100G SKUs was not sourced in our research pass. Check the specific part number's PCIe line before buying, and check your slot's electrical width, not just its physical size - a card in a physically x16 but electrically x4 slot cannot use the lanes it needs.
One QSFP28 connector on one end, four independent SFP28 legs on the other - the standard way a single 100G port electrically is four 25G lanes, split back out into four separate links to four separate hosts. Live listings and the computed cost of a full fan-out are below.
Mixed, and the table states condition per row - several Mellanox and Dell listings are used/renewed enterprise pulls, and one QNAP unit is current-production SMB hardware aimed at exactly this kind of homelab breakout build.
We don't make that call - see each card's own page for its sourced facts (driver, PCIe where available, EOL status, third-party board prevalence) and the live prices above. The two differ meaningfully on how third-party-board-heavy the market is (E810 far more so) and on how completely we could source PCIe/EOL facts (ConnectX-5 far more completely, since ark.intel.com did not render for our Intel research pass).
Specification claims on this page were checked against the pages below on 4 August 2026. Where a widely-repeated figure did not survive that check, we report what the source says now and say so in the text rather than repeating the familiar number.