HP ProLiant Network Adapters — Complete Buying Guide (FLR, FLB, FlexFabric)
Everything you need to know about HP server network adapters — the difference between FLR and FLB, how to choose the right HP 331FLR, 530FLR, 544FLR, or FlexFab
Why HP ProLiant Network Adapters Matter
Choosing the wrong HP network adapter for your ProLiant server is an expensive mistake. Plug in the wrong form factor — an FLB into a rack server that needs FLR, or a standard PCIe card into a FlexibleLOM slot — and you have a paperweight.
This guide covers every HP ProLiant network adapter form factor, the compatible servers for each, and the specific part numbers you should be ordering for common upgrade scenarios in 2026.
HP Network Adapter Form Factors Explained
HP ProLiant servers use two proprietary adapter interfaces in addition to standard PCIe slots:
FLR — FlexibleLOM Riser (Rack Servers)
FLR adapters are designed for HP ProLiant rack servers (DL series). They install in the FlexibleLOM slot on the system board — a dedicated connector that provides PCIe bandwidth directly from the CPU without consuming a standard PCIe slot.
Key characteristics:
- Only fits DL (rack) series ProLiant servers
- Provides lower latency than standard PCIe adapters (direct CPU path)
- Single adapter serves as the primary NIC — you do not need a PCIe riser card
- FLR adapters are labeled with "-FLR" suffix in HP part numbers (e.g., 331FLR, 530FLR)
Which servers use FLR: DL160, DL180, DL360, DL380, DL385, DL560, DL580, DL80, DL120, DL140
FLB — FlexibleLOM Blade (Blade Servers)
FLB adapters are designed for HP BladeSystem blade servers (BL series). They install in the mezzanine connector on the blade module.
Key characteristics:
- Only fits BL (blade) series ProLiant servers
- FLB adapters labeled with "-FLB" suffix (e.g., 530FLB, 554FLB)
- Cannot be installed in rack servers — connector is different
Which servers use FLB: BL460c, BL490c, BL660c (within HP c3000/c7000 blade chassis)
FlexFabric Technology
HP FlexFabric is an adapter technology (not a form factor) available in both FLR and FLB variants. FlexFabric adapters support partitioning — a single physical port can be split into multiple virtual ports (up to 4 per physical port), each with:
- Independently configured bandwidth (Ethernet, FCoE, iSCSI)
- Guaranteed minimum and maximum bandwidth per partition
- Support for mixing Ethernet and storage traffic on a single physical connection
FlexFabric is HP's answer to converged network adapters (CNAs), combining LAN and SAN traffic without separate HBAs.
HP 331FLR — The Standard 1GbE FLR Adapter
The HP 331FLR (part number 629135-B21) is the most commonly installed ProLiant network adapter. It provides:
- 4x 1GbE ports (RJ-45 copper)
- Broadcom BCM5719 chipset
- PCI-Express x4 FlexibleLOM interface
- Compatible with Gen8, Gen9, and some Gen10 servers
HP 331FLR Part Numbers
| HP Part # | Description | Price |
|---|---|---|
| 629135-B21 | HP Ethernet 1Gb 4-Port 331FLR Adapter | ~$102 |
| 629135R-B21 | HP Ethernet 1Gb 4-Port 331FLR Adapter (HPE Renew) | ~$102 |
| 789897-001 | Spare part for 629135-B21 | ~$102 |
331FLR Compatible Servers
| Server | Slot |
|---|---|
| ProLiant DL180 Gen8 | FlexibleLOM Slot 1 |
| ProLiant DL380 Gen8 | FlexibleLOM Slot 1 |
| ProLiant DL380p Gen8 | FlexibleLOM Slot 1 |
| ProLiant DL380 Gen9 | FlexibleLOM Slot 1 |
| ProLiant DL560 Gen8 | FlexibleLOM Slot 1 |
| ProLiant DL580 Gen8 | FlexibleLOM Slot 1 |
Note: The 331FLR is not compatible with ProLiant Gen10 servers (DL360/DL380 Gen10). Gen10 uses the 366FLR series.
HP 530FLR — 2-Port 10GbE FLR Adapter
The HP 530FLR-SFP+ provides dual-port 10GbE connectivity via SFP+ for rack servers.
| HP Part # | Ports | Interface | Connector |
|---|---|---|---|
| 656596-B21 | 2x 10GbE | FLR | SFP+ |
| 656596-001 | 2x 10GbE | FLR | SFP+ |
530FLR Compatible Servers
DL160 Gen8, DL360 Gen8, DL360 Gen9, DL380 Gen8, DL380p Gen8, DL380 Gen9, DL560 Gen8
HP 544FLR — Dual-Port 10GbE/InfiniBand FLR
The HP 544FLR-QSFP is a high-performance dual-port adapter supporting both 10GbE and QDR InfiniBand on the same physical hardware. Used in HPC and high-density virtualization environments.
- Connectivity: 2x QSFP+ (10GbE or 40GbE QDR/FDR10 InfiniBand)
- Chipset: Mellanox ConnectX-3
- Use cases: HPC clusters, large-scale virtualization, converged Ethernet + InfiniBand
HP 561FLR-T — 2-Port 10GbE Copper FLR
The HP 561FLR-T provides dual-port 10GBase-T (RJ-45 copper) at 10GbE speeds, eliminating the need for SFP+ transceivers and fiber cabling. Popular for ToR switch connections where 10GBase-T is used.
| HP Part # | Ports | Connector |
|---|---|---|
| 700697-B21 | 2x 10GbE | RJ-45 |
Compatible with Gen8 and Gen9 DL series servers.
HP 530FLB — 2-Port 10GbE Blade Adapter (FLB)
For BL series blade servers, the 530FLB provides dual-port 10GbE in the mezzanine form factor.
| HP Part # | Description |
|---|---|
| 530FLB | HP Flex-10 10GbE 2-Port 530FLB Adapter |
| 656590-B21 | HP Flex-10 10GbE 2-Port 530FLB Adapter |
HP FlexFabric Adapters — Converged Networking
For environments that need Ethernet and storage (FCoE/iSCSI) over the same physical links:
| Adapter | Ports | Speed | Form Factor |
|---|---|---|---|
| HP 530FLB FlexFabric | 2 | 10GbE | FLB (blade) |
| HP 534FLB FlexFabric | 2 | 10GbE | FLB (blade) |
| HP 554FLB FlexFabric | 2 | 10GbE | FLB (blade) |
| HP 554FLR FlexFabric | 2 | 10GbE | FLR (rack) |
Browse all HP FlexFabric adapters
Gen10 Adapters — 366FLR Series
ProLiant Gen10 servers (DL360/DL380/DL560 Gen10) use the newer 366FLR family:
| Adapter | Speed | Connector | HP Part # |
|---|---|---|---|
| HP 366FLR | 4x 1GbE | RJ-45 | 816551-B21 |
| HP 366FLR-MMSFP | 4x 1GbE | SFP | 816552-B21 |
Important: 331FLR adapters are NOT compatible with Gen10 servers. Always use 366FLR for Gen10.
Quick Selection Guide
| If your server is... | And you need... | Order this |
|---|---|---|
| DL360/DL380 Gen8/Gen9 | 4x 1GbE | HP 331FLR (629135-B21) |
| DL360/DL380 Gen8/Gen9 | 2x 10GbE SFP+ | HP 530FLR-SFP+ (656596-B21) |
| DL360/DL380 Gen8/Gen9 | 2x 10GbE RJ-45 | HP 561FLR-T (700697-B21) |
| DL360/DL380 Gen10 | 4x 1GbE | HP 366FLR (816551-B21) |
| BL460c Gen8/Gen9 | 2x 10GbE | HP 530FLB (656590-B21) |
| Any DL server | Extra PCIe NIC | Intel X520, Mellanox CX-3 (standard PCIe) |
Where to Buy HP ProLiant Network Adapters
Pro Disk Network stocks 500+ HP network adapter SKUs for every ProLiant server generation — from Gen6 through Gen10. All adapters are tested and guaranteed compatible.
- HP 331FLR — 1GbE 4-Port FLR Adapters
- HP 530FLR — 10GbE SFP+ FLR Adapters
- HP 544FLR — 10GbE/InfiniBand FLR Adapters
- HP 561FLR-T — 10GbE Copper FLR Adapters
- HP FlexFabric 10GbE Adapters
- HP 530FLB — 10GbE Blade Adapters
- All HP Network Adapters
For bulk pricing on 10+ units or compatibility questions, email sales@prodisknetwork.com — we respond within 2 hours.