Thanks for this great thread! Recently I installed a WD SN550 1TB into my cousin's 2015 13-inch Macbook Pro. I thought why not contribute something back to the thread by sharing my experience with the new SSD.
First comes first. The main reasons I picked SN550 are 1) its theoretical throughput (2400MB/1950MB) fit nicely with maximum PCIe 2.0 x4 bandwidth available from the Macbook's SSD socket. So no over-spent performance will be left on the table. And 2) the low power requirement as shown in WD
specs.
The maximum 4.9W for the 1TB model from the WD spec sheet appears like an over statement. Below are the power states retrieved by smarttools:
Code:
Supported Power States
St Op Max Active Idle RL RT WL WT Ent_Lat Ex_Lat
0 + 3.50W 2.90W - 0 0 0 0 0 0
1 + 2.70W 1.80W - 0 0 0 0 0 0
2 + 1.90W 1.50W - 0 0 0 0 0 0
3 - 0.0200W - - 3 3 3 3 3900 11000
4 - 0.0050W - - 4 4 4 4 5000 39000
The programmed Maximum is only 3.5W with a typical 2.9W. During benchmarks (BlackMagic & etc), the maximum current I've ever seen from iStat Menu is about 890mA (which coincidentally indicates ~2.9W power). The drive runs cool considering the tight space inside the Macbook. Idle temperature is 35C with room temperature at 24C. Max temperature observed during benchmark is 43C.
About idle power consumption. With display on & no input activity for a minute or two, SN550 idles at 0.26A or 0.00A accodring to iStat Menu. I don't understand the exact logic of transitions but eventually it will idle at 0.00A, meaning beyond measurable.
With NVMeFix, SN550 idles at 0.23A or 0.00A - a reduction of 30mA. Given that the SSD automatically idles at 0.00A most of the time. I won't bother with NVMeFix if its installation is troublesome for you.
Overnight sleep consumes "zero" battery. The catch is that I had to reduce "standbydelaylow" and "standbydelayhigh" from Apple's default 3hr and 24hr respectively down to 25min for both. I picked 25min simply because of the desire to strike a balance between saving battery and reducing wear&tear of the SSD (due to frequent write of hibernation image). A glimpse at the size of /var/vm/sleepimage is only 1GB in my case. Perhaps I should not worry at all.
All in all we're extremely happy with this upgrade. It just shows Apple's SSD prices or 3rd-party made-for-Apple SSD prices are beyond comprehension. If I've to mention any downside of SN550 in general, it'll be the "poor" random 4k write performance.
Note that 2015 13-inch Macbook Pro came with dual core (four threads) processors. From my quick bench using
fio, SN500's random 4k read is about 350k IOPS (close to WD's spec 410k). Given the machine under test is only dual core, I would think 350k is decent. The random 4k write is a miserable 50k IOPS (far below WD's spec 405k). Given the core counts, I give WD the benefit of doubt though I have expected way higher than 50k.
As an aside for OS disk, random read is way more important than random write. So practically I should see little impact on overall performance. With lower core counts & processor performance in these machines (at least 2015 13-inch Macbook), it indicates another reason for not over spending on a high performance SSD.
Last but not least, a BlackMagic screenshot to complete the post. I also put on an unused "heatsink" from my last year's ADATA purchase - it's a thin aluminum sheet with double side tape. The adaptor is a cheap noname from AliExpress.
Hope the post helps someone. Peace out.