May 28, 2013 - This file provides the SATA AHCI driver for Intel 3420-based 11G PowerEdge systems running supported Microsoft Windows OS.
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No reposts, spam, self-promotion or rehosted content. Don’t editorialize titles or submit clickbait. No selling No affiliate links Common Links. General Support Dell support on Twitter: Dell product support:. There has been somewhat of a debate over what the correct / optimal setting should be for the NVMe SSDs in the XPS 13 9350 and XPS 15 9550. The reasons for picking one or the other have changed over time, but there has never been one conclusive answer. My goal here is to try to find that answer, or at the very least compile some relevant information.
Many people received or are receiving their XPS machines in with the SSD set in RAID mode. However, I have personally heard from a few people that after sending their machines back to dell for maintenance, they have been shipped back in AHCI mode. According to information on the Intel’s site about the Rapid Storage Technology driver (the one that is needed during Windows re-installation when in RAID mode) they state that the driver “supports NVMe devices”. When in RAID mode, consulting the machine’s boot menu will show you the controller type listed for the drive is “NVMe” as seen in. This is a good sign, and the correct controller for the our PCIe SSDs. However, the storage controllers listed in Device Manager (in RAID mode) are Intel Chipset SATA RAID Controller and Microsoft Storage Spaces Controller, as seen. For those of you who don’t know, AHCI is a different controller type.
NVMe is a newer controller designed specifically for PCIe-based solid state drives with several advantages over the older AHCI controller. I’m not going to go into detail about what makes them different, just know that NVMe is the controller that we want for our SSD. My goal was evaluate the effect of choosing AHCI mode versus RAID mode when performing a re-installation of Windows 10. I would additionally evaluate the use of using Samsung’s 950 Pro SSD driver, a close relative of the PM951, to evaluate its stability and impact on performance when used in conjunction with AHCI mode. To measure performance differences I used the ATTO Disk Benchmark v3.05 utility and CrystalDiskMark v5.1.2 utility. Windows and its core components were fully updated.
The XPS BIOS was updated to the most recent 1.3.3 version. I first began by running the benchmarks on my current setup, which was still in RAID mode. My machine sports the 256GB PM951 that is rated up to 1000 MB/s reads and 280 MB/s writes according to. The results of the benchmarks showed 1570 MB/s reads and 315 MB/s writes. You can see the results.
These results are likely high due to the synthetic nature of the benchmarks. When compared to other users on my SSD was similar, but landed in the upper 96th percentile with 1348 MB/s reads and 298MB/s writes. You can see my test results. I then went about the process of backing up my computer on an external hard drive, setting the computer to AHCI mode and re-installed Windows 10. Before beginning the process of installing updates and whatnot, I wanted to check the storage controllers in Device Manager. Sure enough, the Intel Chipset SATA RAID Controller was replaced by the Standard NVM Express Controller.
In order to maintain parity, I attempted to then restore my computer from the system image I had just made earlier in the day. I crossed my fingers that it wouldn’t reset the laptop to RAID mode, but seeing as that’s a BIOS option, I assumed it wouldn’t. WELL it didn’t work, I assume because of the disparity between the drivers. I made sure Windows was completely up-to-date after about an hour of restarts, and ran the benchmarks. You can see one of the results. I was on a time crunch and didn’t bother installing screen capture software or tracking down where PrtScr was saving to. I also forgot to take a pic of the 32 GB runs, but believe me it was the same.
BUT THEN through some stroke of magic doo-hickory I was able to re-image my laptop with the backup I had saved – all of my programs and settings were back to the way they were during the first benchmark. I installed the Samsung 950 Pro SSD controller (which only works on AHCI mode) to see if it had any benefit over the standard Windows NVMe controller. After the install, the Samsung NVMe Controller replaces the Standard NVM Express Controller in Device Manager, as seen. I ran the two benchmarks that you can see. So as you can see from the benchmarks I’ve run there is no significant difference in SSD performance between AHCI and RAID mode settings. Using Samsung’s 950 Pro driver off-label has no noticeable impact. However, these results only apply to the 256GB PM951 that I tested.
If you have results that differ or if I did something wrong, please feel free to share. I'm guessing this was brought on mostly by my previous objections to Intel RAID. As I stated previously (and you have actually tested and shown, thank you) the performance difference between AHCI and RAID is negligible.
Intel RAID is not required for the NVMe drives to work (as I stated in how NVMe functions), and just because it works just as well as AHCI and comes by default this does not mean that RAID is more efficient and should be used. Certainly it is no reason to reinstall Windows by it lonesome, if you do not have another reason to reinstall Windows and are happy with what was shipped with your laptop you are all set. However, and maybe this is just the programmer in me, but if there is any unneeded overhead, such as emulating AHCI (even if the performance difference is virtually negligible) it should be eliminated given a convenient option. Sure 1 and 0.99999999 are practically identical, but they aren't exactly the same numbers, so if you're goal is 1, and you get something slightly smaller, while it might not effect you, if you have an easy option to round, you might as well take it.
In this case, if you are going to reinstall Windows anyways, switching to AHCI makes a lot of sense, if for no other reason than the bandwidth and time it will save from from having to find, download, copy over, and then install the RST drivers before installing Windows. Since AHCI doesn't hurt you, and RAID doesn't give you any additional benefits on these systems, no reason to not do it. Also if you want to install Linux, or even think you might want to install Linux in the future, and you are already formatting Windows, unless you are a kernel hacker, you are not going to be able to Install Linux on your NVMe drive right now if it is under RAID, it is as simple as that. So in conclusion (and I think you should add this to the end of your post): If you are already on RAID mode, there is no reason to switch. If you are reinstalling Windows, or adding Linux, for any reason, you may as well go with AHCI.
This test was a long time coming but yes - your objections as comments on my post as well as sparked my action. Just because it works just as well as AHCI and comes by default this does not mean that RAID is more efficient and should be used.' I think you misinterpreted some of what I was saying. Your objection to number 2 has been proven by the actual design of the standard. If you actually read how Intel RAID functions, you will see that while it is extremely efficient in what it does (emulating AHCI), the nature of the technology means it is slightly less efficient.
It is negligible, so it can be ignored, however saying that RAID is more efficient and there for should always be used is a technical fallacy, you yourself proved it here at least with performance. If you are going to reinstall Windows, there is no technical reason to keep using RAID. If the average user is reading a guide onto how to install Windows, it is much simpler to tell them to switch to AHCI than it is to setup RST drivers, consider those drivers which enable RAID offer nothing beneficial over AHCI. Now why AHCI is emulated is very simple: it how it was designed. RAID was designed for SATA drives (as you point out in point 8) and implements the AHCI standard within itself.
It was literally designed in such a way that if a RAID setup is not present it emulated AHCI (and with time it became so good at it that the performance impact became negligible.) Since our NVMe drives don't use either of these SATA standards to interact with the CPU, they only matter in how the Host interacts with the hardware. Intel did not have to change very much on the hardware level to get this to work, only on the software level (hence why you need additional drivers), but the emulation is done on a hardware level, so regardless of what OS and drive type you have running it is going to happen. And those numbers were simply an exaggeration to make a point, I never intended to compare them with the test results.
On my personal tests (which I have no record of to show you) AHCI performed every so slightly better than RAID, because it depends on what the computer is doing at the time, because you are right, it is negligible in the grand scheme of things for performance which is why we shouldn't judge what mode to use based on that. Now you want me to prove that AHCI doesn't hurt battery life, but can you think of a single reason why it would? Especially given how the technologies have developed and what Intel is actually doing, it makes no sense. I'm not going to test it, for the same reason I'm not testing that 1+1=2, what ever results you may come up with will be inconclusive at best. Intel RAID was never designed to improve performance for anything. HOWEVER, even if it did have some effect on battery life, next to the 4K screen, i7, and 960M I have in here, it wouldn't make a dent. Okay the bandwidth thing is the thing that I think you misinterpreted, I meant internet bandwidth here.
Downloading a 100MB driver takes time and bandwidth, both of which in most places in the world cost a fair bit of money, and if ISPs in the US have their way, will cost much more for us too. I currently use on average 1TB of Bandwidth a month.
Comcast wants to cap me at 300GB on my plan. ATT already caps people at 150GB and they don't even offer the speeds I am currently getting. My final statement is not a defeat of the purpose but a statement of the purpose. If you are wondering should you reinstall Windows because of the BIOS settings the answer is no, however if you are reinstalling Windows using AHCI is the way to go.
Since you cannot prove that RAID offers any benefits but does have some (all-be-it minor) drawbacks, and is more complicated than AHCI, it should be switched. I do appreciate what you are doing for the community.
I'm attempting to switch my system from RAID to AHCI via the BIOS. I currently have a DELL M7510 - NVMe PM951 Samsung Drive (Windows) (connected on M.2 PCIe) (factory-installed) - Samsung 850 Pro (connected via SATA) (recently-installed) I'm trying to switch the system from RAID to AHCI but I keep getting the blue screen. I read a similar post a while back and followed the instructions as well as some instructions listed (namely changing msahci, atapi, and IastorV start values to 0).
However, I still am unable to switch to AHCI. Are there any options I can take before trying drastic measures such as re-installing with AHCI on? Thank you, KennethHau. Hi KennethHau, As per the issue description you are willing to switch the system from RAID to AHCI.
Your efforts in resolving the issue is highly appreciated. The Msahci driver in Windows 7 is disabled if the original install was made with the BIOS set to native IDE. The Msahci driver must be enabled before you change the SATA/RAID mode of the boot drive. So, I would suggest you to try the steps provided below and see if it helps you to fix the issue. Registry disclaimer: This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully.
For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: You can use the following link in order to back up and restore the registry in Windows. Hi KennethHau, As per the issue description you are willing to switch the system from RAID to AHCI.
Your efforts in resolving the issue is highly appreciated. The Msahci driver in Windows 7 is disabled if the original install was made with the BIOS set to native IDE. The Msahci driver must be enabled before you change the SATA/RAID mode of the boot drive.
So, I would suggest you to try the steps provided below and see if it helps you to fix the issue. Registry disclaimer: This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: You can use the following link in order to back up and restore the registry in Windows.
If issue persists, I would suggest you to contact the computer manufacturer for further assistance. Kumar, I appreciate the expeditious response tremendously. Unfortunately, I have tried this fix already.
The combinations I have attempted are as follows: atapi, msahci set to 0 atapi, msahci, iastorv set to 0 atapi, msahci, iastorv, pciide set to 0 msahci, iastorv set to 0 Between attempts, I was careful to revert to a known safe registry setup. All of these yield the same result - the loading prompt appears but freezes partway transitioning the the blue screen. I was unable to capture the exact output, but the first sequence was either 0x0.7B or 0x0.78. Are there any other methods aside from a costly re-installation which might fix this? Sincerely, Kenneth Hau. Hi, As per the issue description you are getting blue screen. So, I would suggest you to try the steps pro vided in the article mentioned below and see if it works for you.
Resolving stop (blue screen) errors in Windows 7 Important: While performing chkdsk on the hard drive if any bad sectors are found on the hard drive when chkdsk tries to repair that sector if any data available on that might be lost. Note: I highly recommend backing up all of your important files and folders onto an external storage device before attempting any type of OS repair or upgrade. System Restore disclaimer: When you use System Restore to restore the computer to a previous state, programs and updates that you installed are removed. Note: Ignore the step Reinstall Windows 7 from the above link. Hope this would help. If issue still persists post back with current status of your computer and result of proposed suggestion, we will be happy to assist you.
Regards, Ramesh Kumar.