865408-B21 is the HPE option part number for 500W Flex Slot Platinum Hot Plug Low Halogen Power Supply Kit. It is a hot-plug, redundant plug-in module built to the Flex Slot specification, supplying 500 watts from an AC 100-240V, 50-60Hz input through an IEC 60320 C14 connector. Efficiency is rated at 94% with 80 PLUS Platinum certification. The module measures 2.7 in wide, 8.9 in deep and 1.6 in high, and weighs 32.1 oz. It is listed as compatible with the HPE ProLiant DL360 Gen10, DL380 Gen10 and ML350 Gen10. Use it to populate an empty Flex Slot bay or to add a second supply for redundancy.
HPE Option Part #: 865408-B21
HPE Spare Part #: 866729-001
HPE Model #: 865398-001
HPE Assembly Part #: 865399-101
PRODUCT SPECIFICATIONS FOR 865408-B21:
- Product Type: Power supply - hot-plug / redundant
- Form Factor: Plug-in module
- Specification Compliance: Flex Slot
- Power Supply Compatibility: PC/Server
- Power Provided: 500 watt
- Power Capacity (VA): 563 volt ampere per kilogram
- Voltage Required: AC 100-240 volt
- Frequency Required: 50 - 60 hertz
- Input Connector Type: Power IEC 60320 C14
- Efficiency: 94%
- 80 PLUS Certification: 80 PLUS Platinum
- Compliant Standards: BSMI, CCC, CISPR Class A, C-Tick, cUL, KCC, Low halogen, TUV, UL, WEEE
- Width: 2.7 inch
- Depth: 8.9 inch
- Height: 1.6 inch
- Weight: 32.1 ounce
- Min Operating Temperature: 41 degree Fahrenheit
- Max Operating Temperature: 131 degree Fahrenheit
- Humidity Range Operating: 5 - 95% (non-condensing
COMPATIBLE WITH:
PROLIANT DL SERIES
PROLIANT ML SERIES
** This list may not be complete. Contact us via Live Chat if you have any questions about compatibility.
FREQUENTLY ASKED QUESTIONS ABOUT 865408-B21
What is the difference between 865408-B21 and 866729-001?
They are the same physical power supply under different HPE numbering schemes. 865408-B21, this page, is the option part number: the orderable kit used when configuring or expanding a server. 866729-001 is the spare part number, the same unit stocked for service replacement. This family also includes one assembly revision, one OEM model number and one alternate part number, all listed in the cross-reference block on this page. An assembly number identifies a specific build revision; an OEM model number is the manufacturer's own identifier for the unit.
Which servers does this power supply fit?
The listed compatible systems are the HPE ProLiant DL360 Gen10, DL380 Gen10 and ML350 Gen10. It is a Flex Slot module, so it installs in a Flex Slot power bay on those platforms. Confirm your chassis has a free Flex Slot bay and that your configuration's total power draw is supported before ordering. Power supplies in a redundant pair should match in wattage and efficiency rating.
What input power does it require?
The unit accepts AC 100-240 volts at 50-60 Hz, so it works on both standard and high-line circuits. The input connector is IEC 60320 C14, which pairs with a C13 cord from a rack PDU or wall outlet. Rated output is 500 watts, with a power capacity figure of 563 volt ampere per kilogram. Efficiency is 94% and the unit carries 80 PLUS Platinum certification.
Can it be replaced without powering down the server?
The supply is a hot-plug, redundant plug-in module. In a system configured with redundant power supplies, one unit can be removed and replaced while the server continues to run on the remaining supply. If the server is running on a single power supply with no redundancy, removing it will drop power to the system, so plan for a second unit if concurrent maintenance is a requirement.
What are the environmental and compliance specifications?
Operating temperature range is 41 to 131 degrees Fahrenheit, with operating humidity of 5 to 95% non-condensing. The unit is low halogen and compliant with BSMI, CCC, CISPR Class A, C-Tick, cUL, KCC, TUV, UL and WEEE standards. These marks matter for deployments in regulated regions or facilities with specific emissions and materials requirements. Physical dimensions are 2.7 by 8.9 by 1.6 inches at 32.1 ounces.
Last Updated: 2026-09-01
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This product is warrantied against hardware failure for a period of 1 Year from the date of purchase. Before making a purchase, please take a moment to review our return policy below.
Returns
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