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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BMNify - Thursday, May 15, 2014 - link
"They still do[es] not have one for PCIe-based Macs"so, just get the pci-e card above and use that or even a generic pcie to pci converter and you can install them in your PPC mac, and other systems too, weather they would be accessible booting anything other than a linux PPC distro is another matter OC
Penti - Thursday, May 15, 2014 - link
Macs with PCIe-based SSD's, obviously you could run a discrete PCIe-card (SSD) in a Mac Pro (but that would be SATA/RAID-based not PCIe). PCIe AHCI-based SSD's are only available directly from Apple and made by Samsung and Sandisk, and is only used in recent MBAir, MBP 13/15 and new Mac Pro as well as recent iMacs. There are no third party solutions yet. For previous generations there are solutions and before their own SATA-card SSD they used 2.5-inch drives everywhere except in the Airs. For the 2008/2009 MBA with 1.8-inch drives there are solutions available too. At PowerPC based macs you have either SATA or IDE natively. They just haven't figured out how to produce a PCIe-based SSD for the Macs yet. Over at OWC or anywhere else.RamCity - Thursday, May 15, 2014 - link
Just in case this part was missed in the review here, the XP941 is widely compatible (when installed with an adapter) in the pre-2013 Mac Pro's - all the way back to the 2006/2007 models. The Barefeats.com review is worth a look if you want more information.http://barefeats.com/hard183.html
Penti - Friday, May 16, 2014 - link
The thing I was referring too is that it's not compatible and neither has any compatible modules been made yet for the PCIe-based SSD's of the newer Macs. While earlier SATA-based Apple-custom cards had third party solutions that worked. XP941 is obviously used with a early 2009 Mac Pro with boot-support in the review. So we have number right here. PPC-based systems wouldn't boot it however, even if you might get a Linux-system to recognize it. Which is so far off topic that it's incredible.Penti - Friday, May 16, 2014 - link
Obviously when they have figured out the new connector from Apple the PCIe based controllers should run fine over there on third party cards. Now they just don't exist yet. Like for the thread starters MacBook Pro.Penti - Friday, May 16, 2014 - link
And a early 2013 MBP with SATA-based SSD can use after market SSD's, but not the ones with PCIe yet.Hrel - Thursday, May 15, 2014 - link
256GB SSD, about $100. This one is over $300. Increased speed is nice, but it doesn't matter until they can do it at a better price, closer to the SATA prices the better.I'd be willing to be an early adopter at $200, but I couldn't recommend it to most people until it dropped to $100. I've only recently been able to start recommending SATA SSD's to normal people who don't obsess over every new computer tech.
MrSpadge - Thursday, May 15, 2014 - link
Yeah.. at 3 times the price you'd be far better off using 2 or 3 regular SSDs in RAID - unless you don't have the space and SATA slots for that, like in a mobile workstation.Babar Javied - Thursday, May 15, 2014 - link
Remember when SSDs first came out? they were expensive. But they steadily came down in price and I am sure this will too in due time. Keep in mind that this is new tech and bond to be expensive at first... hell, there is isn't even proper support for it yet.JoyTech - Thursday, May 15, 2014 - link
The benchmark tests only lists results for 512 GB version of Samsung SSD XP941. Are the results same for 256 GB and 128 GB? It is really confusing that this article and previous ones, don't provide those results!