INTRODUCTION

   Thanks to the significant performance gains between PCIe 3.0 Gen3 and PCIe 4.0 Gen4 M.2 NVMe SSDs using DRAM-less NAND controllers makes a lot more sense today than it did even just a couple of years ago and that's obviously why we're starting to see an increase in such models lately. Both the ATOM 50 line by XPG and the FX900 line by HP performed well in my tests and yes even though they clearly can't directly compete with their DRAM outfitted brothers they should be more than sufficient for a vast number of consumers. Well, Silicon Power is one of the latest storage media manufacturers to also release a DRAM-less PCIe 4.0 Gen4 line of M.2 NVMe SSDs and today with me i have 2 out of the 3 available models in it (currently) the UD90 500GB and 1TB.

   Founded in 2003 by a group of enthusiastic data storage industry experts, Silicon Power is committed to delivering outstanding product and service quality. Headquartered and with our own state-of-the-art production site in Taipei, we have become a leading manufacturer of flash memory cards, USB flash drives, portable hard drives, solid state drives, DRAM modules and industrial-grade products. As an international player with four branch offices around the globe, we continuously strive to offer the perfect data storage solution for all requirements of modern digitalized life. With a strong focus on combining innovative technology and award-winning design, we live up to our brand promise to reliably preserve and protect your most valuable data. Because memory is personal.

   The UD90 line of PCIe 4.0 Gen4 M.2 NVMe SSDs by Silicon Power is currently available in 256GB/512GB/1TB capacities and is based on the rather new 4-channel (ARM Cortex-R5 single processor) PS5021-E21 NVMe v1.4 DRAM-less NAND flash controller by PHISON paired with Micron's 176-layer 3D QLC NAND flash (N48R). The PS5021-E21 NAND flash controller by PHISON features their 4th Gen LDPC engine (low-density parity check) along with end-to-end data path protection, Host Memory Buffer (HMB) architecture support (basically takes up a fraction of your PC's system memory to cache mapping tables - only supported on versions of Windows 10/11 launched from 2019 and beyond), wear levelling, low power mode, thermal throttling (70 degrees Celsius limit), TRIM, bad block management, static/dynamic range SLC cache and SmartECC 2.0 (RAID ECC) and fully supports AES-256bit hardware encryption along with TCG Opal 2.0 and Pyrite. Silicon Power covers the entire UD90 line of M.2 NVMe Gen4 SSDs with a 5-year limited warranty and in regards to durability they report an MTBF (meantime between failures) of 1.5 million hours and a TBW of 200 for the 256GB model, 300 for the 512GB model and 600 for the 1TB model.

SPECIFICATIONS AND FEATURES

THE UD90 500GB & 1TB

Silicon Power uses a black and red blister package to ship the UD90 line so from the front you can actually see the top of the drive.

The NVMe version along with contact information for Silicon Power, 2D barcode and numerous certifications are printed at the rear.

As expected just the drives are placed inside the blister packages.

The stickers at the top of both drives are made out of a thin graphene layer to help with heat dissipation.

On one side of the PCB, we find the PS5021-E21 NAND flash controller together with two NAND flash modules for the 512GB model and four NAND flash modules for the 1TB model.

1TB is the maximum capacity for the UD90 so turning the PCB over reveals no available room for a higher capacity model (at least for now).

TEST BED

TESTING METHODOLOGY

   Not long after I first started testing SSDs back in 2008, I concluded that it's almost impossible for any single benchmark suite to accurately measure their performance and that's why in certain benchmark suites we see amazing read/write performance numbers with some drives while in others things are quite different. The reason behind this is that some benchmarking suites are configured to read and write random chunks of data while others read and write constant (sequential) ones. So that's why i always use a very wide selection of benchmarking suites including AIDA64, HD Tach RW, HD Tune Pro, Crystal Disk Mark, Sisoftware Sandra Pro, AS SSD, IOmeter and ATTO. To get the most accurate results each test gets repeated a total of 6 times with the average performance numbers recorded into the charts*/****. Also, as of February 25th 2015 our results will also include the Storage Networking Industry Association’s (SNIA) IOMeter tests. These tests include a 12 Hour write test used to “simulate” performance degradation over time and a mixed workload test which basically shows what you can expect when using an SSD continuously for roughly two hours. Unfortunately, due to the time required for these tests they get repeated a total of 3 times and not 6 as the above.

   Many people have made inquiries about our charts in the past so once again please do keep in mind that the Charts have the average performance numbers of each drive recorded and not the peak (highest) ones. Also, although every single one of these programs can help potential buyers choose the right drive for their needs you should also remember that from any kind of benchmark up to real world usage the gap is not small (and usually most differences will go unnoticed by most people). All tests were performed in a fresh Windows 10 Pro x64 installation complete with every update up to the date of this review.

* Since November 2018 the SSD comparison charts have been divided to 2.5” and M.2 models to reduce their growing size.
** Unless stated otherwise the Ryzen 9 3950x based Test Rig used for M.2 Gen 4 SSD reviews is not located in the lab.
*** As of January 2021 for Gen 3x4 models I’ll be using the Core i9-7980XE test rig (after numerous tests the up to 6% difference in read & write performance compared to the i7-6700 system simply wasn’t enough to justify having an extra test rig around).
**** Since February 2022 M.2 NVMe Gen3 and Gen4 SSD drives are placed in different charts.

TEST RESULTS - AIDA64 / ATTO

TEST RESULTS - HD TACH RW / HD TUNE PRO

TEST RESULTS - SISOFTWARE SANDRA PRO / CRYSTAL DISK MARK

TEST RESULTS - AS SSD / IOMETER

TEST RESULTS - IOMETER SNIA

CONCLUSION

   What stands out in today’s review is without doubt the performance gap between the UD90 line of DRAM-less M.2 NVMe SSDs by Silicon Power and both the FX900 and ATOM 50 models by HP and XPG respectively. This of course is due to the different controller used (Phison PS5021-E21 for the UD90 and Innogrit IG5220 for the ATOM 50 and FX900) so Phison clearly has the lead here (at least in most of my benchmarks) even though reported durability is slightly inferior between models (600TBW / 650TBW). Unfortunately, Silicon Power has once again focused their resources in covering the largest percentage of the market so the UD90 line is only available in 256GB/512GB/1TB capacities (meaning those that sell more). Also, I have to point out that the UD90 1TB variant surpassed even 6500MB/s in reads (in some of my tests) so its actual performance is clearly above what Silicon Power reports.

   Silicon Power officially released the UD90 a few weeks back so availability is still currently very low. So, for now at least I only have the recommended price tags for both UD90 models which should be set at around USD65/75Euros for the 500GB variant and USD95/120Euros for the 1TB variant. Silicon Power hasn’t always had the best pricing available for their products but if these prices do make it to retail the UD90 should become quite the hit among consumers. With that out of the way I really have no complaints from the UD90 models, the Phison E21 controller does a great job (for a DRAM-less model) and durability/endurance numbers although not great should be more than enough for regular use which is why I strongly recommend giving these a chance, they’ll probably impress you with their performance.

PROS

- Very Good Performance (Up to 4800MB/s Read & 4200MB/s Write)
- 5 Year Limited Warranty
- Price (MSRP)

CONS

- Thermal Throttling (During SNIA Tests)
- Current Availability