Much like what we did with the T500 Pro 1 vs 2 Terabyte debate the closer look section is going to be a bit different than usual. To be precise we are going to (mainly) highlight what is different between the two capacity options so as to make it crystal clear what the added expense of the 2TB’er T705 Pro offers ‘above and beyond’ what its smaller sibling can. As such if you want a deep(er) dive into what makes the T705 Pro series tick we do recommend reading the closer look section of the previously reviewed 1TB T705 Pro.
So with that taken care of… lets start with what is the same between the capacity variants.
The first is the shipping container. As expected, it is the same. All that changes when you step up in price is different text on the box. That is fine, as this is not a “special edition” so expecting each and every capacity version to come in a distinctive box… is asking too much. Sure, such clear delineation would make “accidentally” purchasing the wrong option impossible. Sure, it would make excuses over “accidentally” purchasing the wrong model (T500 vs T700 vs T705) also impossible. It just is not practical to expect that. These are not Bentley or Bugatti’s… they are just the SSD equivalent of them. So pay attention when picking one up at your local mom’n’pop / brick’n’mortar store of choice.
On the plus side, we have zero issues with this tastefully attractive shipping container. Some will find it a bit on the bland and boring end of the spectrum, but this is a shipping container you will not feel embarrassed when you hit the front of the checkout line. Furthermore, the internal protection it offers is top notch. Consisting of multiple crumple zones and layers of plastic (in certain directions) this is a box that will fight long and hard to protect its precious cargo. Mix in its light weight and compact form-factor bonus features and it is a box that will not add undue costs to shipping it from Country A to Country B. So it really is pretty much everything you could want in a box.
Also the same is the form-factor. Much like with the T500 1 v 2 debate, it is a bit unusual to see both the 1TB capacity option and the 2TB capacity option have the same form-factor. To be prices we are not talking about the width (22mm) or length(80mm). We are talking about the Z height. To be precise both the nekkid 1TB and nekkid 2TB make use of the ‘D2’ form-factor. Meaning it is populated on both sides of the PCB and the components are up to (but usually a smidgen less than) 1.35MM “tall” on each side of the PCB.
We say this is unusual because these days it is downright easy to find 512GB/4Tbit TLC NAND ICs… and the overall cost of two of them is a rounding error compared to four 256GB/2Tbit TLC NAND ICs. Micron’s B58R may no longer be the density TLC NAND going… but 232 layers of NAND per die level is no joke. This is a good thing™… for 1TB buyers. While it is true that in ‘day to day’ tasks the difference in performance between 2 NAND ICs and 4 NAND ICs will not matter much (as long as each channel is fully populated with dies that it is), there are numerous edge(ish) cases where the extra low level circuitry that 4 NAND IC’s worth of CuA offers does make a difference (especially in overall latency). Put simply, the lower the number of NAND ICs (aka flash package) there are per channel, the better. Better long-term performance. Lower emergency block erasure impact on overall performance. Lower overall latency. Basically, with all else being equal, it is almost always better to have more NAND packages / chips / ICs that are made up fewer die stacks compared to fewer higher NAND ICs with higher stacks of dies.
With that said, the downside to the 1TB’er is the PHISON E26 controller (used on all capacity options… obviously) is an 8 channel controller with each channel being able to handle 3600MT/s worth of bandwidth. Which is great, but Micron 232-layer B58R is 1024Gbit / 1TBit / 128MB per die TLC NAND. 8Tbit total capacity of onboard NAND divided by 4 NAND ICs means that the 1TB T705 Pro each NAND IC only has 2 dies worth of NAND per channel. Still enough to fully/optimally populate each channel but with no extra ‘wiggle room’ worth talking about. This would also be the case if Micr… err… Crucial had opted for two 2Tbit/512GB B58R NAND ICs. As such, the number of NAND ICs is not all that important when comparing the 1 vs 2 T705 Pro.
With each channel also being fully populated the differences between the T705 Pro 1TB and the 2TB capacity option are also basically moot. Some edge cases where the ‘wiggle room’ that goes along with having not 4800MT/s but 9600MT/s of power connected to a 3600MT/s bus… but for most home users the difference is moot.
The same is basically the case from a cooling and compatibility perceptive. Both are high performance dual sided M.2s that require excellent cooling… as they consume about 8 watts (or more) during extended use. This is both a good and bad thing. From an ease of installation perspective the 1v2 T705 series is the exact opposite of the 1v2 T500 series. Crucial could have easily made the 1TB’er single sided and offered a still high performance T705 option that was also extremely easy to install, cool, and generally speaking deal with. Since both are D2s it is moot and there is no excuse to pick the 1TB over the 2TB from either ‘ease of use’, ‘ease of installation’ or even ‘ease of cooling’.
This brings us to the big differences. Of which all favor the 2TB over 1TB. First up the T705 Pro 1TB capacity option has half the amount of onboard RAM cache compared to the 2TB T705 Pro. For most, this too will not matter all that much, but when I/O requests start stacking up the double cache buffer can come in handy to keep the drive ‘fast’.
Equally important is the 2TB has twice as large a pSLC write buffer that is twice as slow to shrink compared to the 1TB T705. Unlike in the T500 1v2 debate, this is actually important. These bad boys can blow through their pSLC cache fast… as Crucial only set it to about 11 percent of free NAND capacity (versus about 20 for the T500). They did because the TLC ‘raw’ speed of this drive is still extremely fast and (as long as the pSLC cache buffer is not exhausted) does reduce overall writes to the NAND (remember pSLC is a buffer and in idle periods it has to be re-written to TLC NAND cells operating in TLC NAND mode).
In theory it does make sense to have the buffer ‘big enough’ but not full blown ‘use it all!!’ sized. The kicker is while, as we have gone over in the past, Phison controller try their darndest to keep ahead of the write requests and will enact emergency block erasures (aka a P/E cycle) before the pSLC is full… it can be overwhelmed causing the ‘3-tier’ write performance that Phison are known for (aka Top performance, background emergency clearance while accepting new write requests, giving up and writing directly to the TLC NAND cells in TLC mode). With PCIe 5.0 controllers being able to squirt nearly 13GB/s worth of data to the NAND a moderate sized pSLC cache buffer on the 1TB T705 Pro really is not enough. Enough to handle copying a modern CoD game’s folder to it, but not enough to do that and anything else at the same time lest it drop down to the middle write performance step/tier. Whereas the 2TB’er can do it and still not drop down from its top write performance tier.
This makes the 2TB a clear and decisive winner over the 1TB. Which is a shame as they could have opted for a 20percent floating buffer… or even 30 percent (as MSI has been known to do). At twenty percent… well… 9 times out of 10 the 1TB option would be ‘good enough’ negating this decisive advantage for the 2TB option.
The last way in which they differ is in the total drive writes they offer. The sky usually appears blue, water makes things wet… and doubling the NAND cells doubles the overall total write count a drive can handle before the warranty is considered ‘fulfilled’. In this case the 1TB’s 600TB Total Drive Write rating is decent and well beyond ‘good enough’ to handle most home users needs for 5 years… but 1200TB is bigger. Giving the 2TB capacity option more piece of mind on the durability and robustness fronts.
Thus the major differences are simple: twice the RAM, twice the NAND, twice the size of pSLC… and twice the endurance. Mix in improved performance and those are the major differences between the two capacity options. Lets turn our attention to the actual performance differences and see if the expected performance improvement is big enough to make it the choice clear.
