
Samsung's 512 GB XP941 is the first four-lane PCI Express M.2 drive in our lab, and we want to know how it performs. In order to figure out what the SSD is capable of, we'll mix up some of the tests from our other storage reviews. First, we benchmark it in ASRock's Ultra slot, which won't limit the device's peak throughput. Then we compare those results to the PCH-attached M.2 slot, which I expect will artificially cap its potential.
Sequential reads and writes are most likely to illustrate my point, so we start there.
Sequential Reads
If you read the previous page, then you won't be surprised by an outcome of 1250 MiB/s in the M.2 slot attached to our Haswell-based Core i5-4670K. A conversion to decimal lands us right around 1.4 GB/s.

Swap the drive over to a PCH-attached M.2 slot, though, and the binary read throughput drops precipitously. Eight-hundred megabytes per second is nothing to sneeze at. But that's still 33% less than the result measured from ASRock's Ultra slot.
Now check out Samsung's otherwise well-reviewed 840 Pro. It looks shabby in comparison, even though we know it to be one of the best SATA 6Gb/s options available. Then again, there's more to the performance story than just sequential throughput.
Sequential Writes
Sequential writes are even more illustrative of the puissant ASRock Z97 Extreme6/Samsung XP941 combo.

And here's why. The 840 Pro gives us almost 450 MB/s of peak bandwidth (again, in binary). Samsung's XP941 in the PCH-attached, two-lane M.2 slot offers a substantial increase, appearing just under 800 MB/s. The SSD should be commended; it can fully exploit a pair of PCI Express lanes, which SanDisk's A110 and Plextor's M6e cannot do.
Then the XP941 jumps up a notch by peaking in excess of 1000 MB/s when we drop it onto ASRock's CPU-attached Ultra M.2 four-lane slot. That's basically what two of the fastest 6 Gb/s SATA drives achieve in RAID 0.
- High-Performance Storage On ASRock's Z97 Extreme6
- M.2 And SATA Express, Discussed
- Z97 Express: The Same Old Bandwidth Limitations
- Testing Samsung's XP941 On Z97 Express
- Results: A PCIe SSD's Sequential Performance
- Results: A PCIe SSD's Random Performance
- Results: Tom's Hardware Storage Bench v.1.0
- Results: PCMark 8 Storage Consistency Test
- ASRock's Z97 Extreme6: Only Satisfied By Samsung's XP941
That said, I feel like X99, NVMe, and and M.2 products will coincide nicely with their respective releases dates. Another interesting piece to the puzzle will be DDR4. Will the new storage technology and next-generation CPUs utilize it's speed, or like DD3, will it take several generations for other technologies to catch up to RAM speeds? This is quite an interesting time
Way to turn things around ASRock! Cheap as chips and rock steady!
PCI-e 3.0 x8 has enough bandwidth for any single card. The only downside to using PCI-e lanes on the SSD applies only to people who want to use multiple GPUs.
Still, though, this is just the mid-range platform anyway. People looking for lots of expansion end up buying the X chipsets rather than the Z chipsets because of the greater expandability. I feel like the complaint is really misplaced for Z chipsets, since they only have 16 PCI-e lanes to begin with.
Well, it'll definitely negate some GPU configurations, same as any PCIe add-in over the CPU's lanes. With so few lanes to work with on Intel's mainstream platforms, butting heads is inevitable.
Regards,
Christopher Ryan
Awww, shucks!
Regards,
Christopher Ryan
SATA3 has a theoretical max of 6Gbps (750MBps). However, the practical max is more around 600MBps.
Assuming you are running your Intel 730's in RAID-0 and achieving the max practical throughput, you'd still only come up with ~1200MBps which is slower than what Tom's saw at 1400MBps ON A SINGLE DRIVE.
SATA3 has a theoretical max of 6Gbps (750MBps). However, the practical max is more around 600MBps.
Assuming you are running your Intel 730's in RAID-0 and achieving the max practical throughput, you'd still only come up with ~1200MBps which is slower than what Tom's saw at 1400MBps ON A SINGLE DRIVE.
SATA3 has a theoretical max of 6Gbps (750MBps). However, the practical max is more around 600MBps.
Assuming you are running your Intel 730's in RAID-0 and achieving the max practical throughput, you'd still only come up with ~1200MBps which is slower than what Tom's saw at 1400MBps ON A SINGLE DRIVE.
SATA3 has a theoretical max of 6Gbps (750MBps). However, the practical max is more around 600MBps.
Assuming you are running your Intel 730's in RAID-0 and achieving the max practical throughput, you'd still only come up with ~1200MBps which is slower than what Tom's saw at 1400MBps ON A SINGLE DRIVE.
SATA3 has a theoretical max of 6Gbps (750MBps). However, the practical max is more around 600MBps.
Assuming you are running your Intel 730's in RAID-0 and achieving the max practical throughput, you'd still only come up with ~1200MBps which is slower than what Tom's saw at 1400MBps ON A SINGLE DRIVE.
Actually, the 4 KB writes are really an artifact of the AHCI controller/API. If you took the same flash and controller on the Sammy, but rigged it to use NVMe, I think you'd see a big bump in random 4 KB performance. I've said over and over that desktop users, for now, are better off by using a couple SATA drives in RAID. More than just adding bandwidth, which isn't always important (strictly speaking), it lowers service times significantly. Plus, it's great to just keep adding cheap drives and getting more performance and capacity (when striped). See the Plextor M6e PCIe review for my thoughts on this.
It's all academic anyway, since you can only buy the XP941 from a few random places, and it's $750. If I had a laptop which could use it, maybe I go that route, but even there SATA is just more power efficient. Give me a 1 TB EVO or M550 instead..... at least for the time being.
PS: Is this Jon C??
Regards,
Christopher Ryan
Totally agree! For now.
I also added the 750 EVO in there because (I believe) the only difference between the 1TB and the 750GB is capacity, unlike the smaller drives, which actually have less performance (i.e. 120, 250, & 500 GB).