Crucial BX500 SATA SSD review

Crucial’s BX500 internal SSD offers a lot of capacity for not so much cash, along with great everyday, real-world performance. Most users will be perfectly happy with this QLC drive, as long as they don’t bang on it too hard—as in writing large amounts of data in a short period of time, or filling the drive to point where it runs out of NAND to treat as cache. At that point, write performance drops to around the hard-drive level.

This review is part of our ongoing roundup of the best SSDs. Go there for information on competing products and how we tested them.

Design and price

The BX500 is a 7-millimeter-thick, super-light, 2.5-inch SATA 6Gbps SSD. It comes in several flavors: The 2TB capacity we tested (currently $200 on Amazon), 1TB ($90 on Amazon) , 480GB ($55 on Amazon), and 240GB ($39.95 on Amazon) of this review. That’s about as cheap as you’ll find, not to mention a rather interesting mix of capacities.

Normally you’ll see 250GB and 500GB drives sold in product lines that feature 1TB and 2TB models, or conversely, 980GB and 1920GB with 240GB and 480GB drives. This is due to the percentage of NAND used for over-provisioning (allotting spare cells as replacements). Crucial obviously feels that the lower-capacity BX500s require more, which might have something to do with intelligent caching. Or not. 

The BX500 employs a Silicon Motion SM2259XT controller. The four NAND chips inside our 2TB test model bore the OBY22NX894 marking. I found no reference to those NAND part numbers online, however, there were four chips on the rather small PC board inside the unit. The large drop in performance after running out of secondary cache during our long 450GB write test strongly suggests that it’s QLC or quad-level cell/4-bit (16 voltage levels).

You won’t necessarily find the same-density NAND chips in the lower capacities. All are rated for the same 540MBps reading and 500MBps writing, so the type of NAND and controller likely remain the same. Crucial does not promise that this product will use the same components throughout its life cycle, however—which could mean your drive won’t perform the same as the one we tested.

Note that the write speed estimate is for a virgin drive with enough NAND available to be treated as SLC cache—there’s no DRAM on board. When the drive runs out of cache, as mentioned, write performance will drop significantly.  

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Crucial’s BX500 makes a great upgrade in capacity for older laptops. Most users will never hit the drive hard enough to experience a write slowdown.


Whatever the componentry, the 2TB BX500 is a very good everyday performer. Most users will never run into write slowdowns, at least with the larger capacities. With the 240GB and 480GB drives, which have far less NAND to employ as cache, you might.

All but the best SSDs slow down when NAND cache is gone, with QLC being the slowest when this occurs. Also, the phenomenon will present itself more frequently in all drives as they fill up and there’s less free NAND available for use as cache. That’s why it’s important to overbuy in terms of capacity with the vast majority of SSDs. 

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