Date: Tuesday , March 05, 2013
It isn't often that we get surprises when we pop open the case of an SSD, but in the case of the ADATA XPG SX900 128GB SSD, things were not as they seemed. This SSD from ADATA, best known to be one of the first SandForce SSDs to feature the expanded capacity firmware, is also the first publicly available SSD to our knowledge to surface with the newest stepping of the venerable SandForce SF-2281.
The ubiquitous SF-2281 has been the go-to SSD controller for an extended period of time. These controllers have become popular with SSD manufacturers due to the fact that these are relatively inexpensive and do not require dedicated firmware teams. SandForce provides reference firmwares with a few easily adjustable variables, streamlining the R&D process required when fielding a new SSD. Mix in the once class-leading speeds and you had a veritable explosion of SandForce SSDs into the market.
The SandForce line of controllers have recently come under assault by newer controllers from Marvell, Samsung, LAMD, and OCZ's Indillinx. In the interim, SSD enthusiasts have been eagerly awaiting SandForce's next generation of controllers with high expectations.
During the wait for the next generation of SandForce controllers, reportedly due in Q3, word has filtered out that a new stepping of the SF-2281 was in the works. This B02 stepping is designed to provide revolutionary improvements in power consumption, with idle power states falling as low as .1 Watts. This is a wise move from SandForce, with the explosion of the mobile market requiring SSD's with meager power requirements.
During initial testing of the SX900 we noticed some unusual power consumption figures, above any SSD we have tested. One of the variables we routinely monitor, the startup voltage of the SSD, was exceedingly high. We were noting peaks of up to 10.9 Watts during this period, and then a 10 second interval of 7 Watts, followed by a reduction into the idle wattage. The highest values we have observed in the past were in the 4 Watt range, so understandably this piqued our interest.
Once we popped the top off the SX900 a brief inspection revealed that the SF-2281 did not have the typical VB1 numbering. The old SandForce controllers are numbered SF-2281VB1-SPC, and this controller features one different number that makes a huge difference. It turns out that this the first B02 stepping SandForce controller (SF-2281VB2-SPC) spotted in the wild, and no one said a word to us or other reviewers about the release.
Curiously enough, we had already been in contact to inquire with ADATA as to why the SX900 was still on the 4.0.2a firmware. This is an old firmware version that does not have working TRIM. We are now several firmware revisions after the TRIM fix came down the pike, and yet ADATA is still using the broken firmware.
Representatives from SandForce have confirmed that this new B02 controller requires the new 5.0.3 firmware to provide the revolutionary new power consumption features, though 5.0.2b features a demo version. Without the correct firmware, do not expect to see any significant power consumption improvements with the SX900. The high initial voltage does seem to indicate that the controller is not running correctly with this older buggy firmware revision, and we are left with more questions than answers at this point. SandForce has replied that the controller should not be surpassing 10 Watts, and we are left to speculate that this is an issue confined to the SX900.
We have contacted ADATA and reported our findings. Its reply states this is expected power performance on boot, and that B01 controllers experience this same power spike. We can confirm from our own testing that this is not the case with B01 controllers. This is also in direct conflict with information provided by SandForce representatives. This prompted several follow-up questions to ADATA representatives, to which we have not received a reply.
With standard Intel 25nm Synchronous NAND in use the ADATA XPG SX900 features speeds that are consistent with expectations from current generation SF-2281 processors. The addition of the new SandForce revision will add some interesting facets to this review as we test the ADATA XPG SX900 against similar SSDs, though it is important to note that the new B02 stepping offers power consumption advantages with no loss of performance.