M.2 Performance Without the Slot



With PCIe 4.0 M.2 NVMe drives holding the desktop storage performance crown currently, and only AMD platforms able to deploy them, we’ve reached a strange place.

Until Intel wakes from the deep slumber, it has enjoyed those that want the fastest possible storage to have only the choice of mounting dual PCIe 3.0 units and RAID 0 striping them to compete. But that option assumes that the computer has dual or more M.2 NVMe slots and lots of computers used every day have none.

Engineers at WD noticed this upgrade dilemma and came up with the WD Black AN1500, a solution that can add NVMe performance to machines that don’t sport M.2 slots and offer better than PCIe 3.0 x4 performance.

Too good to be true? Let’s see if the AN1500 is all WD says.

Design & Build

To the uneducated, the WD Black AN1500 looks like a video card that wasn’t loved enough to get a fan or any means to output its renderings.

Aesthetically it fits with many the WD Black series, having a metal casing that resembles a shipping container and sandwiched between the from and back are the card electronics and a band of colourful LEDs.

The edge connector and endplate identify this as a PCIe slot card, and one that requires a PCIe 3.0 x8 or x16 slot to operate. And, what slot it ends up occupying is important I realised in testing.

As curious as it looks outwardly, where the AN1500 is special is hidden inside. This card is a carrier for two PCIe 3.0 M.2 NVMe SSDs, pre-configured with two WD SN730 NVMe drives in a RAID 0 (striped) mode.

Specs & Features

There are three versions of the AN1500 available offering 1TB, 2TB and 4TB capacities. Each design contains two each of the WD SN730 modules in 500GB, 1TB and 2TB sizes accordingly. This is not a single drive.

The performance in these drives is channelled to the PC using a PCIe 3.0 x8 link via a Marvell 88NR2241 NVMe RAID controller, an Enterprise-class chip.

Therefore, in theory, it can leverage double the performance of a single WD SN730 NVMe drive by using twice as many PCIe lanes as a single M.2 NVMe slot and come close to the performance levels of a single PCIe 4.0 M.2 NVMe.

It can achieve this even if the motherboard has no M.2 slots if it has 8 lanes of PCIe 3.0 available and a suitable slot to be placed.

As I realised when testing, that last statement contains a well-hidden bear trap.

PCI lanes required

Not wanting to pre-empt the benchmark results, but my initial testing didn’t go as anticipated. The AN1500 performed as about half what I had expected. And then I realised that the second PCIe x16 slot on the test system wasn’t offering the card eight PCIe lanes.

Very often in desktop systems, there aren’t enough PCIe lanes to fully operate all the possible uses for those lanes. And, while many boards have multiple x16 physical slots, depending on what else is connected these can be degraded by the system to x8 or x4. And, in my instance, that’s what happened.

To get the full performance of this device, I was forced to evict the video card from the first x16 slot, that always gets the full sixteen lanes, and put the AN1500 there. If I’d have spent extra time on this, I’m confident that I could have disabled a feature and gotten this to work without the swap, but this change worked.

I mention this issue because anyone considering the AN1500 needs to understand how many PCIe lanes they have spare, and if they can direct eight of them to spare slot, hopefully without compromising the video cards performance or anything else.

It is essential to realise that if you place the card in a PCIe 3.0 slot with only four lanes or even a PCIe 2.0 slot, it will work, but you won’t experience the performance levels that it was designed to generate.

LEDs and software

It might seem a minor thing, but this hardware puts on a light show whenever the computer is powered.

By default, this is a rainbow effect that cycles around the edge of the AN1500, and lovely it is in a case where the internals can be seen.

For those that want more control, WD offers a Windows-only Dashboard application that can configure one of thirteen different LED patterns and the colours that it generates.

But this software tool is also the mechanism to update view the status, update the firmware and monitor performance and temperature of the device. It also provides links to a free version of Acronis that WD offers to clone an existing drive to the AN1500 if you want it to become the OS boot drive.

The software isn’t included on the drive or in the box, but instead can be found on the support pages for the hardware.

Performance

As I remarked earlier, get this drive in the wrong slot, and you won’t see what it really can do. Like putting a limiter on a sports car.

Placed in a PCIe 3.0 slot with x8 lanes it exceeded the quoted 6,500MB/s reads, and 4,100MB/s writes in some synthetic tests.

CrystalDiskMark 7.0 it recorded 6,860 MB/s reads and 4,496 MB/s writes, obliterating any single PCIe 3.0 NVMe drives performance Tech Advisor has tested. And that’s unlikely to change since both values are better than the theoretical maximum for a device connected by a PCIe 3.0 using four lanes only.

These typically manage reads in the 3,500 MB/s and writes up to 3,400MB/s on the very best products.

What it doesn’t top are the best PCIe 4.0 M.2 drives that have the same bandwidth as this unit, but can achieve better than 7,000MB/s reads, and 5,000MB/s writes using a PCIe 4.0 NVMe slot.

I tried a range of benchmarks, and they mostly came up with the same narrative; the AN1500 is better than any single PCIe 3.0 NVMe drive, but it can’t match the PCIe 4.0 connected SSDs.

It is also worth noting that like so many NVMe drives the ones inside the AN1500 use SLC memory as a cache to handle sustained writing of large files, and once that cache becomes saturated the performance drops to around 700MB/s, i.e. the real performance of NAND memory.

Except in this design, we have two NVMe drives doubling the size of the cache and also the minimum write performance once the cache is full. For those who move huge files around their system, this last aspect might be a significant strength of this product.

Price

The WD Black AN1500 SSD comes in three options starting with the 1TB unit that costs £228.99 (or $229). The review hardware was the 2TB model priced at £452.99 (or $449.99). And, for those with deep pockets, the 4TB version is £868.99 (or $999.99).

All these prices are directly from the Western Digital Store but you can also get the AN1500 from Amazon or Scan.

In terms of alternatives, a 4TB PCIe 3.0 drive can be found for around $700 from Sabrent, although it can’t match the performance of the AN1500 and it assumes a free M.2 slot.

Another option is the Dell Ultra-Speed Drive Quad NVMe M.2 PCIe x16 Card. It costs around £300/$220, takes four M.2 NVMe cards and boasts read speeds of up to 9GB/s. Installing 4x 1TB drives would still make that path cheaper than the 4TB AN1500 if you have a free x16 slot for it to use.

The Dell card is a shockingly ugly thing that has no LED lights or quantifiable style, but it offers better value if all you want is a fast and flexible storage solution.

Check out our chart of the best SSDs to see what other options you have.

Verdict

What is excellent about the AN1500 is that it enables older systems to have NVMe performance even if they have no M.2 slots. I recently retired an Intel X79 series system that was still remarkably powerful but lacked modern features like M.2 slots, and this would be the perfect companion for that system.

Technically it would have been nice to have the option to configure this as a RAID 1 device for maximum resilience, and the lack of hardware encryption will put some customers off. But it does come with a five-year warranty and the metal enclosure kept the drives inside cool during use.

Performance is much better than PCIe 3.0 NVMe drives, although it ever reaches the throughput peaks that we’ve seen with true PCIe 4.0 hardware, like the Samsung 980 Pro.

The more significant issue here, like so much equipment now, is the cost justification, especially if you want 4TB.

If you like LEDs, have an x8 PCIe slot unoccupied and no free M.2 slots then this might be perfect for your system but expect to pay a premium to have something easy to deploy and visually alluring.

Specs
WD Black AN1500: Specs

Capacities: 1/2/4TB
Capacity tested: 2TB
Tested 4KB performance: 54.30/187.67MB/s
Tested sequential performance: 6860MB/s read, 4496 MB/s write
Quoted sequential performance: 6500MB/s read, 4100MB/s write
Encryption: NA
Flash technology: SanDisk 64-layer 3D TLC
Connection: PCIe 3.0 x16 slot (x8 required)
Warranty: 5 years



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