Trying AHCI Mode (XPS 15 9550)

I've got a new 9550 XPS 15 with Samsung PM951 drive, and wanted to try AHCI mode for some write tests (vs. current Intel RST driver), but I'm not sure how to enable AHCI mode? I've tried changing to AHCI mode in BIOS, but cannot successfully boot that way - I get a BSOD during boot process saying the device is inaccessible after switching from "RAID" to AHCI in Bios.

I'm sure I need to enable or install a driver or something somewhere on the Windows side, but couldn't locate where/how to do this? In device manager I see the "NVMe PM951" under "Disk Drives" and "Intel RAID" and "Microsoft Storage Spaces" under "Storage Controllers", but I'm not sure what to do here. Any help would be much appreciated!

 

Change one-time boot to safe mode. Just before it boots in safe mode bring up the BIOS and change from RAID to AHCI.

 

OK I got it working based on your advice, thank you!

For benefit of others: For safe mode do "Change advanced Startup Options" -> "Restart Now" -> "Troubleshoot" > "Advanced options" > "Startup Settings" > "Restart".

Do F12 immediately on the other side of the reboot to go into BIOS and change to AHCI. After exiting from that, you'll continue with the reboot but enter into the special startup options graphical menu automatically (caused by the special restart option within Windows before the reboot), and you can choose "Safe Mode" (by pressing it's number). That should get you into Windows in safe mode. Login and verify in Device Manager that the disk drives and storage controller sections show nvme and ahci instead of RAID. Reboot again normally and verify that these settings stuck. Voila.

Thanks again.

 

msconfig.exe > Boot > Safe mode still works on W10 and is quicker

 

Please share the results of those tests. I'm wondering what is the difference between the two options.

 

Performance results of my testing with my 256 GB PM951 Samsung SSD. I tested Intel RST RAID driver and in AHCI mode 3 different NVMe controllers.

Note in addition to general performance I was also looking to see if a AHCI and NVMe controller combination would alleviate performance reduction caused by the Sleep/Battery bug.

Drivers/Controllers tested:

• RAID - Intel RST: Intel Chipset SATA RAID Controller, iaStorA.sys, 14.5.2.1088 (7/22/2015), from Dell Support, http://www.dell.com/support/home/us/en/19/product-support/product/xps-15-9550-laptop/drivers
• AHCI - Microsoft: Standard NVM Express Controller, stornvme.sys, 10.0.10586.0 (6/21/2006), seems to come with Windows 10
• AHCI - Samsung: Samsung NVMe Controller, nvme.sys, 1.4.7.16 (10/13/2015), from Samsung SSD download page, look for "Samsung NVMe Driver Installer" 1.0 and labeled as only for the 950 PRO, http://www.samsung.com/global/business/semiconductor/minisite/SSD/global/html/support/downloads.html
• AHCI - Intel: Intel(R) Solid-State Drive P3700/P3600/P3500//750 Series, IaNVMe.sys, 1.3.0.1007 (7/7/2015), from https://downloadcenter.intel.com/do...ate-Drive-Data-Center-Family-for-NVMe-Drivers

All of the above appear to work with the PM951, although the Microsoft AHCI NVMe driver seems to cause random BSODs for myself and others (EDIT: with latest Dell and/or Windows Updates I and others are no longer having random BSOD issues with the Microsoft AHCI NVMe driver). Also, the AHCI Samsung and AHCI Intel often caused the SSD drive to not be found on a reboot (warm boot) on my system. A fresh cold boot always found the SSD drive. For others with the Samsung driver, it seems this doesn't happen as often or at all.

I noticed that the AHCI Intel NVMe driver seems to have reduced 4K and 4K Q32T1 write performance THAT PERSISTS EVEN AFTER IT IS UNINSTALLED. It could be something else, but this 4K write performance drop-off started when I installed the AHCI Intel NVMe driver. If installing the Intel NVMe driver I'd highly recommend a Windows Restore Point (same could be said for all of them).

(Note I did not test Trim, which could be an issue. Seems TrimCheck or a hex editor like HxD can be used to do this. See http://www.win-raid.com/t24f34-Easy-TRIM-test-methods.html for details on some simple ways to test Trim.)

The Intel AHCI NVMe driver requires a manual install - if you run it directly it says something about no related device found. By manual I mean find NVMe controller device in Device Manager under Storage Controllers, update driver, "have disk" thing.

On to Crystal Disk Mark performance results...

Details of test column headers are:

1. Cold boot with A/C adapter plugged in, run test
2. Leaving A/C plugged in but going into Sleep and wakeup again, run test
3. Cold boot from battery, run test
4. Stay on battery, Sleep, then wakeup, run test
5. From above, plug A/C back in, run test

Green enclosed tests were what I thought best performance and no Sleep/Battery related issues. Orange enclosed tests seem to have some degree of Sleep/Battery related performance drop-off, although this may be subjective. (Note file name prefix numbers were just to order the tests - they have no meaning.)

Tests were run with Windows 10 version 1511 (cumulative update) and 01.00.07 BIOS.

YMMV

 

I switched to AHCI and tried to install the Samsung drivers, but now I am confused. I see three drivers, one from Microsoft dating back to 2006, an Intel AHCI driver that looks okay to me, and a Samsung driver that also looks good.


(Somehow the image keeps disappearing after some time. It is here.)

Is this the desired situation, or should I get rid of the Microsoft driver and replace it by something more recent?

I think I do get fairly good Crystal Disk Mark results:

 

If you're stable, that's a good thing.

The Disk drives Microsoft driver for the PM951 is ok (I think the shell driver is dated 2006, but drivers underneath it are later).

Samsung Storage controller is latest one from Samsung, although I've had reboot issues with it. Other's haven't. If you don't have issues leave it. Right now, I have no issues (other than lower performance) with the Microsoft Standard NVM Express Controller, which I'm currently running.

I and others are running an older version of the IDE ATA/ATAPI controllers / Intel(R) 100 Series/C230 Chipset Family SATA AHCI Controller. I'm running 14.6.0.1029, whereas yours shows 14.8.0.1042.

How did you get the newer 10.8.0.1042 version? What I have on my system as options for the SATA AHCI Controller:

EDIT: Just realized 10.8.0.1042 is from a recent Intel RST driver update, which is available here.

 

Interesting... I have the latest Dell, Intel, and Windows updates, so I tried switching from RAID to AHCI and used the Microsoft Standard NVM Express driver. Unfortunately, I got a CRITICAL_PROCESS_DIED BSOD after about an hour of use. I believe I had the 10.8.0.1042 version of the Intel SATA AHCI Controller driver, but not 100% sure. My system has the PM951 512GB hard drive. Maybe this issue isn't completely fixed, or perhaps it could be from me not using a clean install?

On that note, has anyone ever tried using the "Disabled" option for the SATA Controllers in the BIOS? I keep reading about users using AHCI or RAID, but never the Disabled option (unless I missed it). I tried this option briefly just for the heck of it, thinking it wouldn't work at all, but it was still able to detect the hard drive and boot into Windows. (I still used the safe mode trick after making the change, but not sure if it is needed here.) The only difference I noticed in Device Manager is that the "IDE ATA/ATAPI controllers" section did not show up anymore (compared to AHCI mode). It was still using the Microsoft Standard NVM Express driver in the "Storage controllers" section. I ran a CrystalDiskMark test and the speeds remained fast or similar to those I ran in RAID or AHCI mode. Would this 3rd option (Disabled) be anything worth looking into some more? Is there any reason for those of us with only an NVMe drive to NOT use the Disabled mode? It seems like this option might make the most sense considering that NVMe is not SATA, and we don't need to use RAID.

I didn't have time to continue testing the Disabled mode, so I have switched back to RAID for now since it is known to work and I wanted a stable machine for the next few days. I may try switching back to Disabled later to see if I get any BSODs with that, but in the meantime I would be interested in seeing what anyone's thoughts are about using the "Disabled" option.

 

Hey guys,

I changed to ACHI mode but the laptop never boots - it's encountering an "Inaccessible Boot Device" error. Any ideas? I have the 32GB cache model.

Thanks!

 

I think that if you have a HDD with a 32GB SSD cache you *must* use RAID. AHCI will not work in that setup. See this forum thread.

My driver configuration as described a few posts back turns out not to be stable after all. I also have boot problems.

 

Wait, did you just turn AHCI on without removing the cache first? Change back to RAID in BIOS, boot the machine, open RST control panel and remove the cache. And then it should boot in AHCI mode from the 1TB drive, although I don't really know why would you want to do that.

And for the others in the thread - I'm running super stable in AHCI mode for a month already. 950 Pro, no Intel drivers (I have 'standard SATA AHCI controller' with Microsoft driver) and only the Samsung NVMe driver for the NVMe controller in storage controllers. Not a single BSOD.

 

I am currently running AHCI with the standard Microsoft NVMe drivers and the 512GB SSD (PM951). Is it worth to upgrade to a 950 Pro you think? The write speeds currently are pretty underwhelming. Switching to AHCI and using the 950 pro's drivers helped, but upon reboot, I got a BSOD every single time. The reviews of the 950 pro are all very positive, so I'm on the fence.

 

I wouldn't upgrade based on the speed alone. The difference in random operations is negligible. Actually if I knew before that xps m.2 port supports msata I'd just install 850 evo in it instead of 950 Pro. But: the 950 Pro with Samsung drivers is really stable in AHCI, at least in my case, but on the other hand, from all the reports posted here on the forum, PM951 seems to be stable when in RAID mode with intel drivers. I would just enable RAID and stick with PM951.

950 Pro has great benchmarks, but is hot as hell and throttles under sustained load, and eats CPU. It kind of reminds me of the early 90's when we got IDE controllers in Amiga and running in PIO mode was maxing out the poor 25Mhz CPU. And it was only slightly faster than 5 year old first gen internal SCSI interface that didn't have any visible impact on CPU load.

 

Thanks for your quick reply. I'm glad I didn't order the SSD. And I am sad to say that I am returning my XPS.

The problems I had appeared to be solved, but I got 2 more, seemingly random, blue screens today and I am tired of trying to fix it. The errors weren't about the drive so I'm not sure what the problem is now.

I'm sure that in due time, all issues with QC and software will be fixed for this machine, but right now I just need something rock solid stable. I'm going for a macbook because of its high resell value, so that I can come back and buy the Dell again when everything is ironed out.

 

These days, the high resale value on Apple products isn't any better than high-end 'Windows' computers when you factor in purchase price.

I owned the 12" MacBook (512GB model) for a few months and was lucky to get $1200 for it.

Paid $1000 for an XPS 13 not long before that and sold it for $925.

 

I have to disagree. Here in the Netherlands, a 6 month old MacBook Pro (15"/512GB) still easily gets sold for a stunning 2300 euros. Seeing how it costs 2670 in most stores here, I feel that's quite a lot for a six month old machine.

 

Me too! This is the same model I have! the 32GB cache with the 1TB HDD. I want to swap out the lousy HDD with a 2.5 '' SSD. Any ideas? I need specific instructions because I am noob. Or if I can also set up an M.2 SSD for boot and an 2.5 SSD for storage? Or raid?

 

with 2 devices in it, you always need raid mode!

 

Running AHCI mode, what's the fix for the restart-hang with the Samsung drivers? I've had no BSODs but I'm concerned if I uninstall the Samsung drivers I'll get BSODs with the default ones.

 

What do you mean with two devices in you need raid mode? You only need raid mode if you want to create a raid array or run a caching setup.

 

I think there is some confusion/misconception here. The PM951 is NOT an AHCI device, it's NVMe. It doesn't matter what you set the AHCI/RAID setting to, it doesn't affect NVMe performance. As a matter of fact, if you set the SATA mode (it does say "SATA" not "NVMe") to DISABLED, guess what? It still boots! Why? Because those settings are for the SATA ports, not the NVMe slot.

That's why the initial post show similar performance results when set to AHCI or RAID. It's not affecting NVMe interface.

Dell really should put some sort of NVMe settings in their BIOS or at least note that the settings don't affect the NVMe slot.

 

Two devices like: HDD and SSD for Cache...

And for infos about RAID/AHCI option in BIOS read here:

http://de.community.dell.com/support_forums/laptops/f/103/p/5915/21323#21323

 

But only if you're using the ssd as a cache drive. The 9550 works well in ahci with two drives (I ran a 512gb 2.5" ssd with my 256gb 950 pro in my i5).

 

However in raid mode you have no control over which NVMe driver you can install. It is covered by the RST driver and there is no way that I know of around that.

 

Dear all knowing Custom90, really quick. I want to follow in your footsteps. I have a regular 2.5 SSD that I wish to install and am thinking of picking up a m.2 (nvme or not). I just remove all the hardware, plug in my new m.2, and do clean install right? What settings do I leave bios in? Raid, AHCI? and then after clean install just plug in additional 2.5'' SSD? I am noob please help.

 

hah well first I'm far from all knowing.
In regards to your question, you're right, just remove the old hdd and cache drive and put in the new ones and do a clean install. GoNz0 also has some custom .iso's with the drivers and everything already loaded up.
In terms of raid vs ahci that's a whole different debate. I have noticed I get better performance out of my m.2 drive with it being in ahci mode, however I do have a long reboot issue. Raid seems to be more stable, but you will need to copy the intel RST drivers to your USB key in order to do the clean install.

 

Custom90, thanks for the info. I think I won't have to worry about the intel RST driver If I get a USB recovery straight from Dell (they offer it for free) I think because it comes with everything I would need, right? or how do you recommend I make sure I have the intel RST driver? I won't need two USBs right? I've heard no. If I decide to keep the dual storages, I will make sure to keep you posted since I am also thinking of just sending it back and getting a single PM951 with a larger battery and 16GB of ram on Ebay for $1300 (reburbished). Cheers

 

Yeah my hope would be that Dell includes the drivers on their install usb. If it doesn't, that shouldn't be a problem as you can copy them to a usb drive (dunno if the dell ones are read only).

 

Great, thanks for the info. I will just put them on another USB if they are read only. Thanks again!

 

Isn't the speed drop in RAID mode that occurs after sleep, huge? I want to do a clean install on my XPS 9550, but still confused to choose whether AHCI or RAID. What are the problems with AHCI? Stability and battery use?
Thanks

 

Sadly I am not sure about the sleep issues with RAID mode, I've only really ran AHCI after I noticed a difference in performance. The only issue I have is if I restart the laptop it takes 30 seconds to actually restart, powering off is just fine. Others have fixed this by not installing the samsung nvme driver, but it's not a big deal to me.

 

Just received my 9550 (i7/fhd/512ssd), all the drivers were in last version except the WiFi/Bluetooth one, and the bios is version 01.01.19. I only have uninstalled all the dell crapware, and it runs on raid with RST.

Here are my crystal results :


Results seems consistent with the ones posted on the first page, so no need to switch to AHCI or upgrade to a 950 Pro at the moment. I think it's urgent to wait for the next SM961 (or it's brother the 960 Pro) in order to have a real boost on the SSD side.

 

I finally decided to re-image my machine using Gonzo's post. My bluescreens for bad_pool_header / caller were getting out of control on WiFi. I was going once a week to a few every few days, to 4-5 times a day.

I've never had issues on RAID on my 950 Pro. My speeds were always at maximum 2500/1500 and had no issues with sleep either. I switched to AHCI and the blue screens were immediate with any websurfing. Decided to re-image from ground up and try AHCI without intel RST drivers.

 

Stock NVME = BSODs, Samsung NVME = 30 seconds shutdown hang, RAID = sleep performance drop-off. That about right?

 

On my side, no problem on RAID (no BSOD, no hangs etc...). Boot from cold in 10 secs, go to and from sleep mode without any delay, and performance wise, it's really correct.
I didn't tried AHCI with Intel or Samsung driver, but I doubt it's worth a try.

 

Are folks setting their XPS to sleep or hibernate? There are also some hybrid settings right? Anyone? what's better etc...

 

Hybrid is for desktops as it saves a hibernation image before going to sleep so it can hibernate if you leave it asleep until it hits the hibernation timer. Laptops should use sleep then hibernate timers only.

 

Yes, I see. I have mine on hibernate since I am not using it regularly enough to have it on sleep. I think my battery life is also better on hibernate (obviously) I'm shutting it off for now every time. I haven't really had time to play with it. Kudos.

 

Sleep is very power efficient on this laptop

 

I will try sleep mode even though I think I already have and when I come back to open the damn thing the battery is all drained up. I think I've read about this elsewhere. Hibernate is for me. Well see and keep the forum posted.

 

Except when it wakes up by itself :/

 

I'm thinking of keeping this thing for a very long time.. Should I upgrade to 32gb Ram instead of 16?

 

Nah

 

Depends; if the ram usage shows you're maxing out 16gb, then sure upgrade. If not and it's purely for the sake of it, I'd hold off until needed or prices drop. I upgraded from 8 to 32, but was utilizing 8 easily and didn't want to keep popping the case. So I decided to go straight to 32. If mine had come with 16, I would have waited.

 

So... I'll correct my previous post, I have the same bug as everyone, when going to sleep mode, the sequential read performances are divided by two...



So I will try AHCI asap...
That sucks...

 

Don't go to sleep, just stay on hibernate.

 

I'm not sure about the subtle difference between sleep and hibernate, what I've done is just to close my XPS by putting the screen down, then open it again and make this benchmark.

 

Hibernate is better for me, if I put sleep the battery drains. Hibernate is better for me. Or just don't go to sleep ever and just stay awake. #Insomnia

 

Lol Reboot with SSD needs max. 30 seconds, why not to reboot?