This article covers Western Digital WD Red WD40EFRX 4TB。.

Overview

The Western Digital WD Red WD40EFRX is a 4TB 3.5-inch internal hard drive designed for NAS (Network Attached Storage) environments. With a spindle speed of 5400 RPM, a 64MB cache, and SATA 6Gb/s interface, it strikes a balance between capacity, power efficiency, and reliability. The drive is built around WD's NASware 3.0 technology, which optimizes performance in RAID setups and ensures 24/7 operation without degradation. This model has been a staple in home and small-office NAS systems for years. Its CMR (Conventional Magnetic Recording) technology sets it apart from later SMR-based Red drives, making it a preferred choice for users who need consistent write performance in RAID arrays. The 1 million-hour MTBF and 3-year warranty underline its long-term dependability.

Compatibility Guide

The WD40EFRX is a standard 3.5-inch SATA HDD. Key compatibility points: Form factor: 3.5-inch internal bay (desktop PC, NAS enclosure, external USB dock) Interface: SATA 6Gb/s (backward compatible with SATA 3Gb/s and 1.5Gb/s) * Power connector: SATA 15-pin power Most consumer NAS units from Synology, QNAP, Asustor, and others with 3.5-inch drive bays can accept this drive without issues. For desktop PCs, ensure you have an available SATA data cable and a SATA power connector from the PSU. This drive will not fit in 2.5-inch-only bays.

Product Info

The WD40EFRX was originally released around 2014 and remains available through various retailers. Pricing in 2026 typically ranges from $55 to $70 USD, offering good value for a 4TB NAS-grade HDD. The drive carries a 3-year manufacturer warranty. Market positioning: This is an entry-level to mid-range NAS HDD. It uses CMR technology, which is critical for RAID reliability. The later WD40EFAX (SMR) is cheaper but has poorer write performance in RAID. If you find the WD40EFRX at a reasonable price, it is the better choice for NAS builds.

Best Use Cases

Home NAS storage: Perfect for a 2-bay Synology DS220+ or QNAP TS-233 running RAID 1. Provides reliable long-term storage for family photos, documents, and media files. External backup drive: Pop it into a USB 3.0 enclosure and use it as a always-on backup target for a primary PC. The low power draw (around 3.5W) makes it suitable for 24/7 operation. * Silent home server: Its 5400 RPM operation is quieter than 7200 RPM drives, making it a good fit for a media server located in a living room or office. Avoid this drive for tasks that require high random write performance, such as video editing scratch disks or databases. For those, consider a 7200 RPM HDD or an SSD.

Things to Consider

The most important factor is the CMR vs. SMR distinction. The WD40EFRX is CMR, while many newer WD Red drives (e.g., WD40EFAX, WD40EJRX) are SMR. SMR drives can suffer from severe write performance drops after sustained writes, making them unsuitable for RAID arrays. If you are building a RAID, the WD40EFRX is strongly preferred, but it is becoming harder to find as stock dwindles. Also, 4TB is a relatively modest capacity in 2026. Drives like the Seagate IronWolf 4TB (ST4000VN008) are direct competitors and also CMR-based at similar prices. Compare prices per terabyte before buying. Finally, verify that the drive you purchase is indeed the CMR version — some sellers may ship the SMR model without clear labeling. ## FAQ
Q: Can I use the WD40EFRX in a Synology NAS?\nA: Yes, it is compatible with most Synology models that have 3.5-inch bays, such as the DS220+, DS420+, and DS920+. Check Synology's compatibility list for firmware updates, but generally it works out of the box. Q: What is the difference between WD40EFRX and WD40EFAX?\nA: WD40EFRX uses CMR recording, while WD40EFAX uses SMR. CMR offers consistent write performance and is better for RAID configurations. SMR drives are cheaper but can slow down significantly during heavy write operations. For NAS use, prefer the WD40EFRX. Q: Is this drive good for gaming?\nA: It can be used as a game storage drive, but load times will be longer compared to a 7200 RPM HDD or SSD. For modern open-world games, an SSD is strongly recommended. This drive is better suited for archival or media storage.

Product Disclosure (Amazon)

  • Manufacturer: ウエスタンデジタル(Western Digital)
  • Seller: P-LAB
  • Fulfilled by: P-LAB
  • ASIN: B07X6GZ7LT
  • Note: This article covers a manufacturer-made product based on Amazon listing details.