Samsung SSD XP941 Review: The PCIe Era Is Here
by Kristian Vättö on May 15, 2014 12:00 PM ESTBoot Support: Mac? Yes. PC? Mostly No.
Booting from PCIe devices has always been rather quirksome because the BIOSes in motherboards are designed to boot from SATA devices, as they usually do. Most PCIe SSDs and SATA adapters include boot support by loading special drivers before the BIOS, which makes the drive visible in the boot screen. Without the drivers the drive won't show up in the BIOS but once you boot into the OS it will be accessible like any other drive. The problem is, you can't boot from the drive unless it shows up in the BIOS' boot screen.
Unfortunately, the XP941 doesn't seem to include the drivers necessary to enable booting. At least no driver loading screen shows up during boot, which suggests that the XP941 doesn't even have such drivers (ASUS is also telling us that this is the case). I'm thinking that the XP941 is designed for UEFI booting because from what I have heard, you don't need the drivers for UEFI boot but there is still some sort of a UEFI key needed to make the drive bootable. I did try the UEFI boot method on my ASUS Z87 Deluxe board but even though I was able to install the OS to the drive just fine, it wouldn't show up in the boot order.
The good news is that 9-series chipsets bring some ease to the situation. Back when the 8-series was introduced, there weren't many PCIe SSDs on the market but this year we will see PCIe entering the mainstream segment. That obviously forces the motherboard manufacturers to work on PCIe boot support and we can confirm that at least AsRock's Z97 Extreme6, which has a PCIe 2.0 x4 M.2 slot, supports booting from the XP941 out of the box. Whether other 9-series motherboards support booting from the XP941 remains to be seen. Most manufacturers, however, seem to be limiting the M.2 slot to just two PCIe 2.0 lanes, so you wouldn't want to use the XP941 in those boards anyway (unless the XP941 is used in a standard PCIe slot with an adapter). Anyway, we'll be sure to investigate the bootability of the XP941 in our motherboard reviews and work with the OEMs in order to bring better support for PCIe booting.
Update 5/20: ASUS just sent me an email that all their Z97 based motherboards will get a BIOS update that enables booting from the XP941. The BIOS is currently in beta testing and ASUS is expecting public release in about two weeks.
Macs, on the other hand, can boot from the XP941 just fine. I confirmed this using an early 2009 Mac Pro and the volume in the drive shows up in the boot option screen just like any other volume does. I have to admit that I don't know why exactly this is the case, but I'm guessing it's a fundamental difference between how the EFI in Macs and the BIOS/UEFI in PCs handle device recognition.
Under OS X, the XP941 shows up like any other SATA device. Since it utilizes the AHCI command set, OS X thinks it's a SATA device even though it's not. However, it's also listed under PCI cards but the page doesn't provide any meaningful info.
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hulu - Thursday, May 15, 2014 - link
Second page of review, fourth paragraph, states they were only able to aquire the 512 GB version, since as an OEM product Samsung isn't sampling the drive to media.Always helps if you read the entire story before commenting!
JoyTech - Friday, May 16, 2014 - link
In that case, the reviewer better leave out the 128 & 256 GB out or mention the exclusions on first page, not 2nd page, 4th para; a good reviewer should make it easy for readers to access info, not act as lawyers and read the fine print!Also, I forgot to mention that their SSD bench marks have same problem (http://anandtech.com/bench/SSD/730), where they leave out Samsung SSD 840 EVO 250 GB, which is perhaps the best selling SSD in the market now. Very few people give a crap about 1 TB products, which is so proudly displayed in the bench!
Kristian Vättö - Saturday, May 17, 2014 - link
The first page is just an introduction with no mention of the XP941 anyway. It wouldn't have fit the context there and in the end I at least like to think that the reader reads the whole review and not just a paragraph or two. It's rather hard to write something for a reader who reads a part here and part there.As for the 250GB 840 EVO, it is in the bench but we haven't run Storage Bench 2013 on it. That's because the test itself takes around 24 hours to complete and with the strict review times we don't usually have the time to test all available capacities.
critical_ - Thursday, May 15, 2014 - link
Paradoxically, my problem with the M.2 form-factor is the number of sizes available to manufacturers. My Dell Venue 11 Pro tablet has a 2260 size 256GB SSD by Lite-On. There have been lots of firmware issues. The best thing would be to swap it out with a Samsung or Intel variant. However, there isn't much selection out there and 2260 is an oddball size. I'd like a 1TB mSATA SSD but it doesn't exist.Lenovo was smarter in this regard. Their Yoga 2 Pro uses the newer connector for the wireless card but the SSD is plain old mSATA. This allows me to pick from a variety of options without size concerns.
I know I'm ranting and it is still early in the M.2 game but I hope manufacturers settle on providing high capcities in the 2242 and 2260 sizes with plates (like half mPCI-E to full mPCI-E) to allow them to fit in bigger slots.
Babar Javied - Thursday, May 15, 2014 - link
Getting a smaller drive to fit into the bigger slot is easy. As you said, this can/should be easy with the use of "plates" or "expansion cards". So give it some time and you should have lots of options for your device. Should the 2260 size still remain an oddball, you can always get a 2242 size with extensions to help it fit into the bigger slotsdstarr3 - Thursday, May 15, 2014 - link
All due respect to the awesome performance the new interface promises, I still feel like it's going to be a while before the 6Gbps bottleneck makes my computer feel frustratingly slow.darwinosx - Thursday, May 15, 2014 - link
Read the benchmarks or ask someone who has been using PCIE SSD on a Mac for some time now. It's much faster and noticeable.Calista - Friday, May 16, 2014 - link
But also highly depending on what you're doing. Maybe most people are accepting a slight drop in performance in exchange for less issues with compatibility and the option of moving the drive to a second machine down the line or mounting it in a usb cabinet.Sabresiberian - Thursday, May 15, 2014 - link
I have 2 issues with PCIe as a storage interface, at this point in time.First is that, for me, as a high-end gaming PC user, the number of PCIe lanes to the CPU is already limited. SATA lanes are not since I simply don't use that many storage devices. The second is cost. A few weeks ago I bought 2 480GB Sandisk Extreme II's for $300 each, and just saw them for $260 each listed on Newegg - so, for less than the cost of a 512GB XP941 I can get around twice the storage at similar speeds if I install using RAID 0 using current high-end SSD devices.
Until Intel and/or AMD decides to provide more direct PCIe lanes and the cost comes down, PCIe SSDs are just an interesting upcoming technology, for me. :)
SirKnobsworth - Thursday, May 15, 2014 - link
At least on an Intel platform, you wouldn't normally be using lanes from the CPU for a storage device (which are usually dedicated to graphics) - you'd be using lanes from the chipset (of which there are usually 8).