SK Hynix SC308 SSD Review

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512GB Performance Testing

Comparison Products

Our test lineup reflects the current state of SATA SSDs. You'll notice that nearly everything uses 3-bit per cell NAND. You can still purchase the Samsung 850 Pro 512GB, but it costs a whopping $269.99! You will have better luck with the SanDisk Extreme PRO 480GB at $219.99, but only a few online retailers still have stock. Inventory has dwindled as SanDisk transitions to 3D and planar TLC for all consumer products.

The TLC SSDs will lower your AMEX bill; most 512GB class products are priced around $150. The $159.99 Crucial MX300 525GB is one of the more popular SSDs. The SK Hynix SL308 500GB, also with TLC NAND, weighs in at $159.99. The OCZ Trion 150 480GB carries the same price point. The Intel 540s 480GB and Mushkin Triactor 480GB raise the bar at $184 and $192. The Samsung 850 EVO, long considered the best mainstream consumer SATA SSD, shoots up to $199.99.

Sequential Read Performance

To read about our storage tests in-depth, please check out How We Test HDDs And SSDs. We cover four-corner testing on page six of our How We Test guide.

Sequential reads don't tax SSDs like many of the other workloads, so most of the products are similar. The difference is nearly a rounding error throughout the entire queue depth (QD) range.

Sequential Write Performance

TLC-based SSDs rely on advanced cache technology that employs a small portion of the TLC NAND as SLC. The native TLC sequential write performance measures between 100 MB/s to 200 MB/s for most of the SSDs. The Samsung 850 Evo is the sole exception thanks to Samsung's advanced flash technology. The SK Hynix SC308 doesn't rely on an SLC cache to absorb the sequential write traffic. That's both a blessing and a curse because SLC cache is faster than native MLC. Some of the other products use a fairly large volume of SLC area until the drive is half full, which provides a performance boost. Conversely, the SC308 delivers more consistent performance, and you won't get frustrated when you write data to a nearly-full drive.

Random Read Performance

The SK Hynix SC308 knocks it out of the park with over 9,000 random read IOPS at QD1. The drive scales really well before it reaches peak performance of nearly 100,000 IOPS at QD32.

Random Write Performance

The advanced SLC cache in the 850 EVO and MX300 is capable of very high QD1 random write performance, but the MLC SC308 isn't far behind. Again, we see very good performance scaling as the workload intensifies.

80 Percent Mixed Sequential Workload

We describe our mixed workload testing in detail here and describe our steady state tests here.

The TLC SK Hynix SL308 had problems with mixed sequential performance. The MLC SC308 follows the same trajectory in our test.

80 Percent Mixed Random Workload

SK Hynix really needs to optimize mixed workload performance to deliver a better user experience. This topic will come up in the next section of the review when we test application performance.

PCMark 8 Real-World Software Performance

For details on our real-world software performance testing, please click here.

The low mixed workload performance really hurts the user experience, and that shows in the PCMark 8 Storage test. The SC308 can outperform all the other SSDs, but the firmware and dual-core processor favors simple tasks like 100-percent reads or writes.

Application Storage Bandwidth

I would have to say the drop off between synthetic and real-world application testing is the largest we've ever seen. This is a significant issue given the SL308 with TLC flash manages to outperform the MLC-based SC308.

PCMark 8 Advanced Workload Performance

To learn how we test advanced workload performance, please click here.

The SK Hynix SC308 delivers exceptional performance under heavy workloads. The drive is amazing for heavy audio and video editing, but it just can't convert that into high performance during lighter workloads. The Phison S10-based products have the same problem.

Total Service Time

The service time tests reveal nearly identical performance between the two Sx308 Hynix SSDs, but the results differ during the moderate section of the test. That's where the drives have time to rest and flush the cached data, so the SL308 with SLC cache has the technology advantage. It took quite a bit of engineering to get TLC to consumer performance levels. Unfortunately, when TLC development began the rapid pace of MLC advancements slowed. The companies simply allocated their engineering resources elsewhere.

Disk Busy Time

The SC308 would otherwise be considered an amazing SSD. It's a good fit for sustained heavy workloads.

Responsiveness Test

We run the BAPCo SYSmark 2014 SE Responsiveness test in a Lenovo Y700-17 gaming notebook. You would see higher performance in our desktop systems, but this platform allows us to show the devices in a mainstream computer with average specifications. Both SK Hynix SSDs are at the bottom of the responsiveness list. We can point to the mixed workload tests as the reason.

Notebook Battery Life

The Notebook Battery Life test with BAPCo's MobileMark 2012 v. 1.5 is one test we can't explain. The SL308 500GB performs very well in this test and even leads the group. The new SC308 falls to the bottom of the battery life chart.


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Chris Ramseyer
Chris Ramseyer is a Contributing Editor for Tom's Hardware US. He tests and reviews consumer storage.