The ADATA XPG SX950 480GB SSD Review: In Search of Premium

Sequential Read Performance

Our first test of sequential read performance uses short bursts of 128MB, issued as 128kB operations with no queuing. The test averages performance across eight bursts for a total of 1GB of data transferred from a drive containing 16GB of data. Between each burst the drive is given enough idle time to keep the overall duty cycle at 20%.

For short bursts of sequential reads at QD1, the ADATA XPG SX950 comes reasonably close to saturating the SATA bus and is not significantly outperformed by any other SATA drive.

Our test of sustained sequential reads uses queue depths from 1 to 32, with the performance and power scores computed as the average of QD1, QD2 and QD4. Each queue depth is tested for up to one minute or 32GB transferred, from a drive containing 64GB of data.

On the longer sequential read test, the SX950's performance drops dramatically, leaving it as one of the slowest SSDs in this bunch.

With such poor sustained read performance, the SX950's efficiency is quite low, though all the other drives with Intel/Micron 32L 3D NAND also rank at the bottom of this chart with the SX950 even when they deliver higher performance.

ADATA XPG SX950 480GBIntel SSD 545s 512GBSamsung 850 EVO 500GBSamsung 850 PRO 512GBPNY CS1311 480GBPNY CS2211 480GBSanDisk Extreme Pro 480GBCrucial MX200 500GBCrucial MX300 525GBADATA Ultimate SU800 512GBOCZ Trion 150 480GBOCZ VX500 512GBCrucial BX300 480GB

Sustained sequential read speeds on the ADATA SX950 do not increase with higher queue depths. The burst test showed that higher speeds are possible in favorable conditions, but giving the SSD more work to do when it is already bottlenecked internally doesn't help things.

Sequential Write Performance

Our test of sequential write burst performance is structured identically to the sequential read burst performance test save for the direction of the data transfer. Each burst writes 128MB as 128kB operations issued at QD1, for a total of 1GB of data written to a drive containing 16GB of data.

The burst sequential write speed of the SX950 is about average, and virtually identical to its TLC-based SU800 sibling; this test is primarily hitting the SLC caches so it's unsurprising to see the two perform the same.

Our test of sustained sequential writes is structured identically to our sustained sequential read test, save for the direction of the data transfers. Queue depths range from 1 to 32 and each queue depth is tested for up to one minute or 32GB, followed by up to one minute of idle time for the drive to cool off and perform garbage collection. The test is confined to a 64GB span of the drive.

The sustained sequential write speeds of the SX950 fall short of the top SATA drives and are instead slightly lower than the Crucial BX300, but since this test doesn't fill the drive the SX950's write performance doesn't end up falling through the floor.

The SX950's power efficiency during the sustained sequential write test is pretty good, though the Crucial MX300 and OCZ VX500 still manage to beat it. The SX950 has about a 20% advantage over the BX300, which is the next most efficient drive using 3D MLC.

ADATA XPG SX950 480GBIntel SSD 545s 512GBSamsung 850 EVO 500GBSamsung 850 PRO 512GBPNY CS1311 480GBPNY CS2211 480GBSanDisk Extreme Pro 480GBCrucial MX200 500GBCrucial MX300 525GBADATA Ultimate SU800 512GBOCZ Trion 150 480GBOCZ VX500 512GBCrucial BX300 480GB

The SX950 doesn't reach full sequential write performance until QD4, and its saturation speed is slightly slower than drives like the Samsung 850 PRO (which is very nearly at full speed by QD2). Performance and power consumption remain steady through the second half of the test as the drive still has plenty of SLC cache remaining.