The HP 631683-B21 is a Flash-Backed Write Cache capacitor pack with a 610mm (24-inch) cable, designed for HPE Smart Array controllers in ProLiant Gen8 and Gen9 servers. It provides backup power to the FBWC module during unexpected power loss, ensuring cached write data is safely committed to flash memory. Unlike traditional batteries, the supercapacitor design offers a longer operational lifespan with no scheduled replacement cycles and no temperature-related degradation.
This is the short-cable variant (24") designed for 1U chassis configurations. The long-cable variant for 2U+ chassis is 660093-001 (36"). This is a high-volume replacement part in TPM market as ProLiant Gen8 and Gen9 servers remain widely deployed.
WHERE IT FITS
TRANSCEIVER→POWER_CABLE→631683-B21
SPECIFICATIONS
Part Number
631683-B21
Manufacturer
HP
COMPONENT DIAGRAM
KEY FEATURES
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Flash-Backed Write Cache Capacitor
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610mm (24") Cable Length
Compact cable for 1U chassis installations
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Supercapacitor Technology
Longer lifespan than traditional batteries — no scheduled replacement cycles
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Hot-Plug Capable
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No Maintenance Required
TYPICAL APPLICATIONS
RAID cache protection during power loss events
Write-back cache enablement for storage controllers
Enterprise server data integrity assurance
Hot-swap battery/capacitor replacement in production