The SK Hynix Platinum P51 internal solid-state drive (starts at $199.99 for 1TB; $319.99 for 2TB as tested) is the South Korean chip maker's first venture into the PCI Express (PCIe) 5.0 SSD arena. It leverages the semiconductor company's expertise, with its main components sourced in-house. The P51 has blazing throughput numbers and performed well on most of our tests, but it's not a dazzler like the five-star WD Black SN8100, our current PCIe 5.0 favorite. The P51 would be a clearer choice at a lower price, and we'd like to see it in capacities higher than 2TB.

Design: Homegrown Components, DRAM Cache

The Platinum P51 is a four-lane solid-state drive running the NVMe 2.0 protocol over a PCIe 5.0 bus. This internal SSD comes in the standard M.2 Type-2280 "gumstick" format. This drive is single-sided (it keeps all its chips on one side), and uses all homegrown (as opposed to third-party) components: 238-layer Hynix 3D TLC (V8) NAND flash and a Hynix Alistar controller. (Baffled by some of this lingo? Check out our handy guide to SSD jargon.)

The Hynix controller has its own dynamic random access memory (DRAM) cache, as opposed to recent DRAM-less PCI Express 5.0 drives such as the Crucial P510 and Addlink G55H, which instead rely on the computer's host memory buffer (HMB) for caching.

SK Hynix designed the P51 with power efficiency in mind. It's designed to consume a maximum of 10 watts (10W), but that's not actually an exceptional figure—the Editors' Choice-winning WD Black SN8100's power consumption maxes out at 7W, and other SSD makers have highlighted the power savings of their recent Gen 5 offerings as efforts continue to make PCIe 5.0 SSDs mainstream.

We always recommend that users employ a heatsink for PCI Express 4.0 or 5.0 SSDs, but SK Hynix does not currently offer the drive in a version bundled with one. You'll want to make sure your motherboard (and it'll almost certainly be a desktop board you put this drive on) has an adequate thermal solution for the PCIe 5.0 slot you intend to use.

System Requirements: A Store-Bought or DIY Gen 5 Rig

PCIe 5.0 SSDs, even power-efficient ones such as the P51, promise a major throughput speed boost over PCIe 4.0 drives, but you can take full advantage of it only if you have recent hardware that supports the standard. Recent enthusiast desktops and a few high-end laptops are likely to be PCIe 5.0-ready off the shelf, but otherwise, you may have to build your own PC from the ground up or update an existing system to gain the connectivity required. For a desktop, you'll need an Intel 12th Gen or later Core CPU with a motherboard based on Intel's Z690 or Z790 chipset, or a later one; or an AMD Ryzen 7000 or 9000 processor with an AM5 motherboard built around an X670, X670E, or B650E chipset, or later ones.

(Credit: Joseph Maldonado)

Now, an important point: Just because you have one of those chipsets doesn't guarantee that the motherboard maker actually implemented a PCIe 5.0-capable M.2 SSD slot or slots. That's up to the board maker, so check your system's or motherboard's specs and documentation to make sure you actually have such a slot before investing in one of these drives. (Some boards have PCIe 5.0 expansion slots for graphics cards and other PCI Express cards, but you need a PCIe 5.0-capable M.2 slot, specifically.)

Price and Capacity: Expensive, and a Low Ceiling

With most PCI Express 5.0 SSDs coming in capacities of up to 4TB, and with several manufacturers promising 8TB versions of their existing Gen 5 drives, the Platinum P51's 2TB maximum capacity feels cramped. It's also on the pricey side, retailing at this writing in the $250-to-$260 range, which is comparable to some premium SSDs such as the WD Black SN8100.

The Platinum P51 shares a rated durability—expressed as lifetime write capacity in total terabytes written (TBW)—with the lion's share of Gen 5 SSDs we have reviewed, including the Samsung 9100 Pro, the Teamgroup Z540, the WD SN8100, and the Crucial P510, T700, and T705 in the capacities they have in common. Its durability rating is a notch below the ADATA Legend 970, the Aorus 10000, the Corsair MP700 Pro, and the Lexar NM1090 Pro, which are rated at 700TBW for 1TB and 1,400TBW for 2TB. And the Seagate FireCuda 540 is the reigning Gen 5 durability champ, with ratings of 1,000TBW for its 1TB stick and 2,000TBW for 2TB.

The TBW spec is a manufacturer's estimate of how much data can be written to a drive before some cells begin to fail and get taken out of service. SK Hynix covers the P51 with a warranty of five years or until you hit the rated TBW figure in data writes, whichever comes first. But the drive's durability rating is such that unless you're writing unusually large amounts of data to the SSD, it's a good bet that the P51 will last the full warranty period and beyond.

Performance: True to Its Sizzling Speed Rating

In benchmarking the Platinum P51, we used our latest testbed PC, designed specifically for benchmarking PCIe 5.0 M.2 SSDs. It is built around an ASRock X670E Taichi motherboard with an AMD X670 chipset, 32GB of DDR5 memory, one PCIe 5.0 x4 M.2 slot (with lanes that have direct access to the CPU), and three PCIe 4.0 slots. The system sports an AMD Ryzen 9 7900 CPU using an AMD stock cooler; a GeForce RTX 2070 Super graphics card; and a Thermaltake Toughpower GF1 Snow 750-watt power supply. The boot drive is an ADATA Legend 850 PCIe 4.0 SSD. (The reviewed SSD is tested as a secondary data drive.) The motherboard employs an air-cooled (fan-based) heatsink over the PCIe 5.0 M.2 slot that can be placed over the tested SSD, as I did when benchmarking the P51.

(Credit: Joseph Maldonado)

We put the P51 through our usual internal solid-state drive benchmarks: Crystal DiskMark 6.0, UL's PCMark 10 Storage, and UL's 3DMark Storage benchmark. The last measures a drive's performance in several gaming-related load and launch tasks. Among the comparison drives seen in the tables below, I included not only most of the Gen 5 SSDs we have reviewed, but two of the fastest PCI Express 4.0 SSDs we have come across: the WD Black SN850X and Micron's Crucial T500.

Crystal DiskMark's sequential speed tests provide a traditional measure of drive throughput, simulating best-case, straight-line transfers of large files. We use this test to determine if our tested speeds align with the manufacturer's rated speeds.

The P51 effectively matched its sizzling rated throughput speeds in our Crystal DiskMark testing, turning in the third-fastest sequential read speed (behind the Samsung 9100 Pro and WD Black SN8100) and the second-fastest sequential write speed (behind the SN8100). Its 4K speed results were more mundane, with an average 4K read score among our comparison group, though far short of the SN8100, which stood alone at the top of the heap. Its 4K write score is at the bottom of a very narrow range of scores that includes all the PCI Express 5 SSDs except the Samsung 9100 Pro, whose score is much lower and similar to the two PCIe 4 SSDs in our comparison group. Good 4K write performance is especially important for an SSD used as a boot drive, though we test them as secondary drives.

The PCMark 10 Overall Storage test measures an SSD's speed in performing a variety of routine tasks such as launching Windows, loading games and creative apps, and copying both small and large files. The P51 performed well on this benchmark, with the fourth-highest score, behind the Crucial T705, the Samsung 9100 Pro, and the WD SN8100. On the individual trace tests that, when aggregated, comprise the Overall Storage results, the P51 turned in a top score on the Overwatch and a second-best score on the Battlefield 5 launching traces. Its Call of Duty Black Ops 4 score was the worst, though, well below even the two elite PCI Express 4 SSDs we included for comparison.

On the 3DMark 10 gaming-centric benchmark, the Platinum P51 turned in a middling score, amid a pack of Gen 5 SSDs with similar scores, though well short of the high scorers on this test, the Crucial T705 and WD SN8100, whose results were nearly identical.