Dell Precision M4800 SATA speeds (2.5", mSATA, and optical bay)

I'm in the process of purchasing a bunch of new hardware for my home office, and have been having a heck of a time finding authoritative information about the capabilities and interoperability of some of the devices. Having spent several tens-of-hours in recent weeks researching and testing, I'd like to post a series of threads with my findings, in hopes of saving others from having to make the same monumental effort to answer seemingly simple questions. This is the first such post.

The topic at-hand pertains to my new Dell Precision M4800 laptop. Seeing how its successor (Precision 7510) debuted less than a week after I received the M4800, this probably isn't great timing. Still, I'm sure others will upgrade storage in their M4800s over the coming years, so let's try to set the record straight on the options.

Note that my goal here is to state definitive facts about the M4800 storage options, as a reference. But, I also have a question for the group on how to quantify SATA port performance before I can finish writing the reference information. So, even if you don't care about M4800 storage, per se, please scroll to the "where I need your help" part below if you are knowledgeable about storage benchmarking.

What I know so far is:

FACT 1: The M4800 can support up to three internal storage devices

• One, 2.5" hard drive (HDD) or solid state drive (SSD) in the primary drive bay
• One, mSATA card, in the mSATA/WWAN slot (assuming that that slot is not already being used by a WWAN card; there's only space for one device)
• One, optical bay device, which can either be:
  • Actual optical drive (e.g. DVD-ROM), or;
  • 2.5" HDD or SSD, with an appropriate caddy to allow that form factor to fit into the larger optical bay

My evidence for this is:

• I can see it, per the annotated photo below:

• The official Dell Precision Mobile Workstation M4800
  Owner's Manual says so on page 75:

• The product configuration page offers 3 drives when you go to buy an M4800. The whole page is too big for a reasonable screenshot, so I collapsed the drive configuration widgets to just show their titles.Observe the following:
  • 3 total drives
  • "Hard drive" is mSATA type (i.e. "Full Mini Card Installed in Mini Card Slot"); the configurator raises an error if you choose a 2.5" drive for both the "Hard Drive" and "Secondary Hard Drive" options
  • No optical drive; the configurator raises an error if you choose both the "Optical Bay Hard Drive" and "Optical Drive" options

There are several other facts that I would like to state about the M4800 storage configuration options, but do not have enough evidence yet to say either way. Specifically:

• All references I have found, authoritative and non-authoritative, state that the SATA connector for the 2.5" drive bay is SATA 3 / 6 Gbps
• Some references state that the mSATA and optical bay SATA connectors are SATA 2 / 3Gbps, while others state that they are SATA 3 / 6Gbps

It is important to know the speed of the SATA ports because of the presence of the mSATA port (which must be an SSD) and the prevalence of SSDs in general today. Even affordable, consumer-grade SSDs require more than 3Gbps bandwidth to run at their maximum potential. I won't muddy this thread with the details of my own use case, other than to state that I'm looking to purchase additional storage for my M4800 and the SATA port speeds will determine which drives/caddies I buy for which slots, and whether or not I can keep my optical drive in the machine.

To make a very long story short, the owner's manual states that the mSATA and optical bay ports are SATA 2 (see screenshot above). Dell ProSupport confirms that these ports are SATA 2, but won't tell me how they determined that. I've asked them two other hardware questions this week, and it turns out that they were wrong about both of those, so I'm suspect about their answer for this, in light of other evidence.

Perhaps most convincingly, in another thread on this forum (post #456), someone named Dell-Mano_G states:

"Just to respond to some misquotes: Both the M4800 & M6800 mSATA ports are SATA3 spec, 6GBs."

From his "Company Representative" tag in that post, his various posts on the "Direct2Dell: The Official Dell Corporate Blog" site, and the fact that he is generally well-regarded among the web community, Dell-Mano_G appears to be a legitimate authority on the M4800. Still, after several requests, Dell ProSupport will not offer an explanation that reconciles the information they're giving me (SATA 2) with what their colleague has posted here (SATA 3).

There are also numerous other forums and websites that suggest that the mSATA/optical ports are SATA 3, and that the owner's manual is incorrect. I won't itemize them here because they're not authoritative, but there's enough smoke to suggest that there may be a fire.



[UPDATED 2015-12-09]

Based on information gathered subsequent to the initial post, I'm adding a second fact, for posterity, so future readers don't have to read the entire thread.

FACT 2: All three internal SATA ports support SATA 3 / 6 Gbps speed

My evidence for this is:

• The performance benchmark results in posts 8 - 12 on this thread
• The concurrence of other respondents on this thread that the ports should be / are SATA 3

The remaining text below is from the original post, and is now out-of-scope. It doesn't look like there's strikethrough formatting, so I'm dimming the obsolete text to a light gray color.


Now, where I need your help is determining empirically what the speed of the mSATA and optical bay SATA ports are.

I currently have a slow, 2.5" HDD in the main 2.5" bay. After much deliberation, I just ordered an mSATA card with a SATA 3 interface and 500+ MB/s read and write performance (Samsung 850 Evo 500 GB); this will arrive in two days. I also have an existing 2.5" SSD that I can use for testing (Samsung 840 Evo 500 GB), and would be willing to buy some mSATA > 2.5" and 2.5" > optical bay caddies, in the interest of science.

I've done some disk benchmarking before, but I'm not an authority on the matter. What I'd like to do is run some tests that will stand up to the scrutiny of those that are authorities on storage benchmarking - before I start configuring this machine for production use. Once I get an OS/apps/data/etc. on there, I'm not going to want to burn it down to run destructive write tests, for example.

So, my question is:

• QUESTION: What tests would you recommend that I run, using what software, that 1) will determine whether the mSATA / optical bay SATA ports are SATA 2 or SATA 3, and 2) will satisfy the most critical onlooker that the results are legitimate so I don't need to go back and run the tests again?

I just bought an AIDA64 Extreme license, and have an older PassMark license. After spending close to $5K in recent weeks on new equipment, I'd really prefer not to buy any more stuff, including benchmarking software. So, if there's an free option that will do the trick, let's go that way.

Thanks, in advance, for your help - and for making it this far, if you read the whole thing

 

The optical bay is SATA III.


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@alexhawker - Thanks for your reply. If I may ask:

• How do you know that the optical bay is SATA 3?

I've read a lot of posts where people assert this, then others cite the doc and ask for confirmation, then... no one ever follows up with evidence. It stands to reason that the optical (and mSATA) port is SATA 3. The QM87 chipset supports 4 x SATA 3 and 6 x SATA 2 ports (plus an eSATA port). For a machine with only 3 SATA ports (plus one eSATA port), it'd be silly to use the slower channels when there's enough faster ones to go around. Unless, of course, there's some other advantage to using SATA 2, like power savings or something.

From your sig, it looks like you have an M4800 with 2 x 2.5" SSD. If that's correct, I'm guessing that you've checked the speed first-hand and know that the optical bay port is SATA 3. If you've got a report or a screenshot or something that illustrates that, would you mind posting it?

BTW, I ended up ordering 2 caddies this afternoon - one mSATA-to-2.5", and the Newmodeus 2.5"-to-optical bay (thanks for your post about that on the other thread, too!). I decided that it would drive me nuts if I didn't test each port first-hand, so I broke down and got them. The kids won't eat tonight, but we'll know by Tuesday how fast this machine is.

 

I can run a benchmark later if you like, but I definitely get better than SATA II speeds on the SSD in the optical bay. It's the larger of the two in my sig, and the one my O/S is on. The others actually got Win 10 on it at the moment but I've been using 8.1 and haven't touched that in a while so I should probably just format the other drive and put Linux back on it.


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I would expect the mSATA / WWAN slot to be SATA 3. This is the configuration on the Latitude E7440 and I doubt Dell would make the Precision worse than the Latitude.

John

 

Agreed - It would be surprising in general for a notebook this recent to have any drive bays connected at SATA II speeds.


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All Haswell notebook SATA ports are SATA 3 speed... So both drive bays and mSATA slot should be running at SATA 3 speeds...

 

I've finished testing my M4800 with a handful of storage configurations, and the speeds of all three ports - mSATA, 2.5" bay, and optical bay - are faster than SATA 2. It doesn't look like I can attach a zip file of test results, so I'll make a series of follow-up posts with the relevant screenshots.

The tests included various combinations of the following components:

• Three M4800 slots / bays with SATA connections:
  • mSATA / WWAN slot
  • 2.5" drive bay
  • Optical bay
• Three drives:
  • 2.5" 2TB 5400 RPM HDD that came with the machine
  • Samsung 840 Evo 500 GB 2.5" SSD
  • Samsung 850 Evo 500 GB mSATA SSD
• Two adapters/caddies:
  • StarTech mSATA-to-2.5” adapter (SAT32MSAT257)
  • Newmodeus 2.5”-to-optical bay caddy (OBHD9-SATA-SATA-B)

I tested most permutations of drives/bays. Some combinations were physically incompatible (e.g. 2.5" drive in mSATA slot). Others I didn't test extensively (2.5" bay speed, which everyone agrees is SATA 3). One long-running test I cut off early because we had to leave for Thanksgiving vacation I also didn't have a 2.5" drive that I could use for destructive write testing, so some configurations only include the read tests. Lastly, I didn't run the buffered write test, per a warning in the AIDA64 Extreme documentation stating that it can cause premature wear on the first few blocks of an SSD.

Overall, the M4800 is completely stock, other than having run Windows Update and installing AIDA64 Extreme. I literally haven't done anything to it since receiving it, other than installing the aforementioned drives for running these tests.

In summary, the results showed:

• The mSATA port runs faster than SATA 2 speeds for reads and writes
• The optical bay runs faster than SATA 2 speeds for reads and writes, when using an actual 2.5" SSD in the Newmodeus caddy
  • The speeds are considerably slower when using the mSATA SSD in the mSATA-to2.5" adapter, then using that in the 2.5"-to-optical bay adapter; I'm not sure why, but that's not a configuration that I plan to use, so I didn't bother looking into it further.

The 2.5" drive bay also runs faster than SATA 2; that port speed wasn't in dispute, but the tests confirmed what we already knew.

I'll post the test next. The file names use the structure <port>__<drive>__<test>.png

 

Test Series 1
Drive bay: mSATA slot
Drive: Samsung 850 Evo 500 GB mSATA SSD
Caddy: None


Read Tests








Write Tests

 

Test Series 2
Drive bay: 2.5" bay
Drive: Samsung 850 Evo 500 GB mSATA SSD
Caddy: StarTech mSATA-to-2.5"


Read Tests








Write Tests

 

Test Series 3
Drive bay: Optical bay
Drive: Samsung 840 Evo 500 GB 2.5" SSD
Caddy: Newmodeus 2.5"-to-optical bay

Read Tests


Write Tests
None; I had data that I needed to preserve on the 840, so could not perform the write tests.

 

Other Tests

The following are some additional tests I conducted that are less useful than the three test series described above, but that I am including in the interest of being comprehensive.

Firstly, here are two read tests summaries for the 2 TB 5400 RPM HDD:

In the 2.5" bay



In the optical bay, via the Newmodeus 2.5"-to-optical bay caddy




Next, here are a series of read tests for the Samsung 850 Evo 500 GB mSATA SSD in the optical bay. To physically connect this drive in this bay, I first mounted the mSATA drive in the StarTech mSATA-to-2.5" caddy. Next, I mounted that assembly in the Newmodeus 2.5"-to-optical bay caddy. Interestingly, the performance was poor compared to other configurations that used either of the caddies alone. I don't know why this is, but am not planning to investigate further, as this isn't a configuration I plan to run in production.

Read Test




Write Tests

 

With all of the above tests as evidence:

• Can we conclude with certainty that all three SATA ports in the M4800 - mSATA, 2.5", and optical - are SATA 3?

I assume that we can, but I'd like confirmation from others who are more knowledgeable about hardware than I am. For some of the full-disk tests, it seems like the only explanation for the sustained fast speeds would be a real SATA 3 interface. But, if there's a cache, compression, or some other magic in there that could yield these numbers on a SATA 2 interface, I don't want to jump to the wrong conclusion.


FYI, I received further confirmation from Dell technical support since starting this thread that the mSATA and optical bay ports are SATA 2. Per the analyst who is helping me, this information was obtained from other documentation, not from testing. I forwarded a copy of these test results along with the question immediately above. I asked for clarification if there's an explanation for these speeds on a SATA 2 port. Otherwise, I asked for them to update the doc to reflect that the ports are, indeed, SATA 3. I'll post back as I learn more from Dell.

 

None of the ports are SATA II!!!!! We discussed this in the owners thread already. With such a new CPU, there's no reason any drive connected should run at SATAII speeds. You've already demonstrated you're getting better than SATA II speeds and still you're doubtful?

Dell tech support agents are worse than clueless. Don't believe them.

I'd expect the poor performance from the dual caddy setup - that's hardly surprising.


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Relax, friend. I mean no offense by continuing to ask questions on this thread. But, as far as I know, you're just some dude on the internet saying that the ports are SATA 3. That's why I'm trying to be diligent in arriving at an unassailable conclusion, even if my method seems pedantic.

Maybe there's some more substantive discussion on the "owners thread", but so far, everything I've read, on every forum, from Dell and otherwise, is just a bunch of people asserting that the ports are either SATA 2 or SATA 3 and providing no evidence to support their claims. Even on this thread, you previously offered to provide a benchmark from your own system, but haven't uploaded the results yet. You're under no obligation to do so, and I greatly appreciate your offer to help - along with all of your feedback so far. All else being equal, though, without such a benchmark, it's your word against Dell's. Considering that they're the manufacturer, and I'm paying them hundreds of dollars for technical support, I have to assume that the balance is in their favor unless someone can demonstrate otherwise.

In this case, it appears that you are, indeed, correct. Based on my amateur knowledge of SATA, it seems conclusive to me that the ports are SATA 3. Based on the enthusiasm of your last response, I'm even more convinced. Still, I don't know what I don't know, which is why I asked for confirmation from someone who does know about storage. I'd rather get flamed for being overly-cautious about interpreting my test results, than to draw the wrong conclusion and get flamed for overlooking the "SATA 2 turbo mode" or something that makes things seem faster than they area (I'm making that up, obviously, but you get the point).

Anyway, we seem to be in agreement, so if anyone else thinks the ports are still SATA 2, speak now or forever hold your peace.

 

I agree that all the SATA ports on this notebook are SATA 3 but I would expect nothing less from a recent Precision notebook. The effective limit of SATA 2 is around 250 MB/s.

However, if owners of other notebooks with optical drives stumble across this thread and are thinking of replacing the optical drive with an SSD then I would caution them that there are plenty of notebooks in circulation that use SATA 2 for the optical drive interface. Most optical drives can't max out SATA 1.

John

 

A quick update on my Dell support incident on this topic. After repeated requests, the support analyst who is helping me has put in a request for someone to review the documentation:

"I wanted to let you know the request to confirm and update the system documentation has been passed on to the appropriate department. While I cannot guarantee a change, it will be checked on to confirm its accuracy. "

Just in time for the M4800 to be phased out in favor of the 7510.

Anyway, I'm calling it quits here. I've lead the Dell horse as close to the water as I can.

 

More info for the discussion:
Using the Samsung magician support app and a Samsung 850 EVO mSATA, the app reports that the SATA interface is only SATA 2/3G (and not SATA 3/6G).
Using a Samsung 850 EVO in either the HDD bay or the optical bay reports that it's SATA 3/6G in either place.

 

What version of Samsung Magician are you using?

I currently have the 850 EVO in the mSATA slot and Magician 4.9 reports it as being SATA 3 / 6Gbps:





Maybe there's something else that's affecting the speed, or at least the reported speed, like AHCI?

 

Wow. I sign on to say thanks to you guys for taking the time out to post up such useful technical posts. Especially you, manniongeo.

I do have a question... there appears to be another mSATA port just north of the port replicator connector. MydigitalSSD is marking their 50mm mSATA as compatible for the M4800. And I've seen others referencing that port as usable for it (which would make it a 4th HDD option). What's your take on this ?

 

I looked into this when I first got the M4800. I don't remember the details at this point, but I ruled it out as an option at the time based on some forum posts that I read.

From a quick search to refresh my memory, it appears that that slot (labeled "1/2MC(PP)") is intended for an optional encryption processor from Dell. It looks like it would fit half-height mSATA card, but I recall others stating that it doesn't work, or the speed is slow, or something like that. Here's a post (#883) where the author apparently tried it and found that the slot did not work. He doesn't describe how he determined that, so it's probably worth doing some more research if you're seriously looking at this as an option for another SSD.

If you do find more definitive information or end up testing it yourself, please post your results here. Thanks.