To configure PCIe expansion on a Dell PowerEdge R720, first identify the server model, installed processors and riser configuration; then match the card to a slot’s link width, bracket height and length. The R720 has up to seven expansion-card positions, but slots 1–4 require both processors. The R720xd has a different layout and supports up to six cards, so do not use the R720 slot map for an R720xd.
Check the server model and processor count first
Confirm whether the chassis is a PowerEdge R720 or R720xd before choosing a slot or riser. Dell’s Owner’s Manual lists up to seven supported expansion cards for the R720 and six for the R720xd; the R720xd does not support the default R720 riser 3.
Also check whether both processors are installed. Dell states: “To use PCIe slots 1 through 4 on the riser, both the processors must be installed.” CPU population therefore affects whether those positions can be used, even if a card fits physically.
Use the R720 slot map to choose a position
Dell’s R720 slot information describes the following positions. “x8” and “x16” identify the slot’s link width; they do not describe the card’s bracket height or length.
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| Slot | Riser | Bracket height | Card length | Link width | Processor condition |
|---|---|---|---|---|---|
| 1 | Riser 1 | Low-profile | Half-length | x8 | Both processors must be installed for slots 1–4 |
| 2 | Riser 1 | Low-profile | Half-length | x8 | Both processors must be installed for slots 1–4 |
| 3 | Riser 1 | Low-profile | Half-length | x8 | Both processors must be installed for slots 1–4 |
| 4 | Riser 2 | Full-height | Full-length | x16 | Both processors must be installed for slots 1–4 |
| 5 | Riser not specified in the cited slot summary | Full-height | Full-length | x8 | Check Dell’s slot diagram for processor association |
| 6 | Default riser 3 | Full-height | Full-length | x8 | Check Dell’s slot diagram for processor association |
| 6 | Alternate riser 3 | Full-height | Full-length | x16 | Check Dell’s slot diagram for processor association |
| 7 | Default riser 3 | Full-height | Full-length | x8 | Check Dell’s slot diagram for processor association |
The table reflects Dell’s PowerEdge R720 Owner’s Manual and Technical Guide slot information. The alternate riser 3 changes slot 6 to x16; confirm the exact riser installed in the server before relying on that position.
Check a card against the slot before installing it
A card’s connector may fit while its dimensions, electrical requirements or software support make it unsuitable. Compare the card documentation with the server configuration on each of these points:
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- Chassis: Dell R720 8Bay 2.5" Hot Swap PSU
- Processors: 2x Intel Xeon E52640v2 2.00GHz 8 Core
- Memory Configuration: 64GB RAM (4x16GB PC310600R
- RAID Card: Modular Dell H310 PERC RAID Controller
- Hard Drives: 4x Empty Drive Tray for 2.5" R-Series
- CPU connection: Verify the slot’s processor association and confirm that the required processor is installed. Slots 1–4 require both processors.
- Link width: Compare the card’s required or preferred PCIe link with the slot’s x8 or x16 link width. A slot’s physical connector and its electrical link width are not interchangeable concepts.
- Bracket and clearance: Match low-profile or full-height brackets and half-length or full-length clearance.
- Riser and power: Confirm the installed riser variant and check the card manufacturer’s power requirements. The slot map alone does not establish card-specific power compatibility.
- Firmware and operating system: Check the card’s firmware and driver requirements for the intended system and OS.
- Priority and cooling: Follow Dell’s card-priority and slot-priority guidance for mechanical fit and cooling, particularly when installing multiple cards.
Dell’s slot information does not establish that every third-party PCIe card is supported. Check the exact adapter and system configuration rather than relying on connector fit alone.
Install or reseat a riser safely
PCIe slots in the R720 are not hot-swappable. Shut the system down and disconnect power before working inside the chassis; use the server’s service documentation for the complete safety and removal procedure.
- Confirm the replacement riser is intended for the R720 and matches the desired slot configuration.
- Align the riser with the system-board connector and guide pin.
- Lower it into place until it is fully seated.
- Close the system, reconnect power and install any required device drivers.
These alignment and seating steps follow Dell’s riser installation procedure. Do not force a riser that does not align with the connector and guide pin.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Check firmware settings if a card is missing
If a correctly installed card is not detected, distinguish a firmware setting from a physical-fit, processor, riser or driver issue. Dell’s BIOS Integrated Devices documentation describes Slot Disablement and SR-IOV controls. Slot Disablement is not a general performance adjustment: Dell says to use it only when an installed peripheral prevents the operating system from booting or delays startup.
- Recheck the model, riser type, slot dimensions and processor requirements.
- Confirm the card is fully seated and the riser is fully engaged.
- Review BIOS Integrated Devices settings if the issue points to a disabled slot or SR-IOV configuration.
- Confirm the card’s firmware and operating-system driver requirements.
Use the BIOS instructions for the installed system firmware version for exact menu navigation; the cited Dell material establishes the controls but not a version-specific click path.
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