# What is limiting my SSD speed?



## Rusuran (Oct 14, 2020)

I have just bought a new SSD - Samsung 860 EVO and decided to compare its speed to my old 840 EVO. The results seem strange, as both of them fail to come close (especially 860) to advertised read/write speed (at least the read speed should be above 500 MB/S). 840 EVO is 120 GB (1st image), 860 EVO is 250 GB (2nd image). What could be the cause of lower speeds?


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## Rei (Oct 14, 2020)

Is this on desktop or laptop? If desktop, try swapping the SATA cable. It could be a bit faulty. Make sure to TRIM them SSD as well. Also update the firmware & BIOS.


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## EarthDog (Oct 14, 2020)

With the information you gave us (none), it's tough to even guess. What hardware is this plugged into? What ports on that motherboard are these plugged into? 

You're aware that for all intents and purposes, these drives are similar in speeds right? They both do ~550 MB reads though the 840 is 410MB in writes. IOPS are similar as well.

That said, something is limiting both drives in some way. So, yeah, how about some information please..........


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## ThrashZone (Oct 14, 2020)

Hi,
Have you used samsung magician to update the firmware yet ?


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## Flaky (Oct 14, 2020)

The SSD is probably running on a dedicated SATA3 controller that works on a PCIe 2.0 x1 bus, hence the limit.


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## EarthDog (Oct 14, 2020)

Flaky said:


> The SSD is probably running on a dedicated SATA3 controller that works on a PCIe 2.0 x1 bus, hence the limit.


That was my guess too...hence the ask for more (read: any) information.


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## Rusuran (Oct 14, 2020)

Sorry for the initial lack of info. It's a desktop. Both drives are connected to SATA 3.0 ports 0 and 1 on the mobo (Gigabyte H77-DS3H (rev 1.1)). Swapping the cables didn't help.



ThrashZone said:


> Hi,
> Have you used samsung magician to update the firmware yet ?


It says the latest firmware is already installed.


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## ThrashZone (Oct 14, 2020)

Hi,
You're doing better than my 860 pro and 13 year old q9550 system lol


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## claylomax (Oct 14, 2020)

Have you tried another program other than CrystalDiskMark?


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## Rusuran (Oct 14, 2020)

claylomax said:


> Have you tried another program other than CrystalDiskMark?


I also used Samsung Magician.






ThrashZone said:


> Hi,
> You're doing better than my 860 pro and 13 year old q9550 system lol
> View attachment 171783


Does that mean the platform is limiting the SSDs and there's nothing really to be done?


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## xman2007 (Oct 14, 2020)

Rusuran said:


> I also used Samsung Magician.
> View attachment 171791
> 
> 
> Does that mean the platform is limiting the SSDs and there's nothing really to be done?


No his looks like a sata2 limit


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## ThrashZone (Oct 14, 2020)

Hi,
860 is a weird release and cheap frankly compared to 850 series think even the warranty was less can't remember on 860.


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## dragontamer5788 (Oct 14, 2020)

H77? That's pretty old.



Rusuran said:


> Does that mean the platform is limiting the SSDs and there's nothing really to be done?



H77 is still PCIe 3.0. But Intel's DMI was never that fast, especially if we're looking into older systems like H77. Its quite possibly the H77 chipset itself that is the bottleneck.

As for "what can be done", you might be able to get a PCIe 3.0 connection. If you plug it into the correct port, you might be able to get a PCIe x4 to SATA adapter and run the SSD directly into the CPU. But there's no guarantee that this would be any faster. (Just... something to try if you wanted...)

Its not like SSDs of this speed were available back when the H77 was made. So there's no reason for those older chips to test I/O at these speeds. You're clearly faster than SATA 2.0 (3.0 Gbps), but you're not getting the full 6Gbps theoretical (which would be 500+GB/s). Its hard to imagine where and why this is happening. I only have guesses.


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## ThrashZone (Oct 14, 2020)

Rusuran said:


> I also used Samsung Magician.
> View attachment 171791
> 
> 
> Does that mean the platform is limiting the SSDs and there's nothing really to be done?


Hi,
I was just showing what my really old systems read/ write is on a 860 pro 256gb yours is newer than my 775 socket


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## Flaky (Oct 14, 2020)

My bet is on SATA controller being in IDE mode. 


Check "SATA Mode Selection" in bios to make sure about that.
Keep in mind that you can't just change this setting - the OS needs to be prepared to load different disk driver.


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## Rei (Oct 15, 2020)

xman2007 said:


> No his looks like a sata2 limit


Nope. His speed is way over the SATA II speed limit. It's just not close to SATA III speed limit.


dragontamer5788 said:


> H77? That's pretty old.
> 
> 
> 
> ...


I agree with @dragontamer5788 assumption & possible solution.
Dunno if it will help or make any difference but also try to update the chipset firmware/driver as well as your BIOS.


Flaky said:


> My bet is on SATA controller being in IDE mode.
> 
> 
> Check "SATA Mode Selection" in bios to make sure about that.
> Keep in mind that you can't just change this setting - the OS needs to be prepared to load different disk driver.


Wouldn't IDE be below even SATA I speed? His speed is above SATA II speed.


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## xman2007 (Oct 15, 2020)

Rei said:


> Nope. His speed is way over the SATA II speed limit. It's just not close to SATA III speed limit.
> 
> I agree with @dragontamer5788 assumption & possible solution.
> Dunno if it will help or make any difference but also try to update the chipset firmware/driver as well as your BIOS.
> ...


SATA2 is limited to 300MB/s, not way over that at all, are you quoting my quote or just me?


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## bug (Oct 15, 2020)

Also check device manager. Make sure there's no warning sign there.


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## Rei (Oct 15, 2020)

xman2007 said:


> SATA2 is limited to 300MB/s, not way over that at all, are you quoting my quote or just me?


I'm commenting to you: @xman2007 . As you said: SATA II is limited to 300MB/s. But OP's speed is over that, passing over SATA II limit but not reaching 400MB/s in his CyrstalDiskMark benchmark or 450MB/s in his Samsung Magician benchmark which means that OP is not limited to SATA II. Looking at ThrashZone's benchmark though, his might be on SATA II interface or cable since his didn't go over the 300MB/s SATA II speed limit.


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## Caring1 (Oct 15, 2020)

0% usage so I'd guess the cache hasn't had enough data to get up to speed.


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## Rei (Oct 15, 2020)

Caring1 said:


> 0% usage so I'd guess the cache hasn't had enough data to get up to speed.


I don't think cache is required for attaining high speed since it's benchmarking. Also OP seems to be using it as a storage drive since it's not on C:\ drive.


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## Flaky (Oct 15, 2020)

Rei said:


> Wouldn't IDE be below even SATA I speed? His speed is above SATA II speed.


IDE protocol in itself doesn't have hard limitation, just as AHCI protocol also doesn't have one 
Hard limits come from interface's physical and signalling modes.



Rei said:


> I agree with dragontamer5788 assumption & possible solution.


DMI has the same performance as PCIe, and having 4 links, it gives us ~1.5GB/s limit, well above OP's results.
That's the numbers people are getting when they connect NVMes to chipset-attached PCIe on DMI2 platforms.


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## Rusuran (Oct 15, 2020)

dragontamer5788 said:


> As for "what can be done", you might be able to get a PCIe 3.0 connection. If you plug it into the correct port, you might be able to get a PCIe x4 to SATA adapter and run the SSD directly into the CPU. But there's no guarantee that this would be any faster. (Just... something to try if you wanted...)


I have only 2 SATA 3.0 ports, other 4 are 2.0.

Anyway, thank you all for the help and suggestions. I don't think a bit of performance left out will be noticeable for my use case (gaming), so I'll leave it at that.


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## ThrashZone (Oct 15, 2020)

Rei said:


> I'm commenting to you: @xman2007 . As you said: SATA II is limited to 300MB/s. But OP's speed is over that, passing over SATA II limit but not reaching 400MB/s in his CyrstalDiskMark benchmark or 450MB/s in his Samsung Magician benchmark which means that OP is not limited to SATA II. Looking at ThrashZone's benchmark though, his might be on SATA II interface or cable since his didn't go over the 300MB/s SATA II speed limit.


Hi,
Yes my old one is sata 2


			acer wg43m mainboard specs


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## Flaky (Oct 15, 2020)

Rusuran said:


> Anyway, thank you all for the help and suggestions. I don't think a bit of performance left out will be noticeable for my use case (gaming), so I'll leave it at that.


Please check mentioned setting in bios or at least run AS SSD benchmark (it displays used driver, and it's enough to tell IDE/AHCI modes apart) and show results.
Don't just leave us with unsolved mystery


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## ThrashZone (Oct 15, 2020)

Hi,
Op's system isn't that old to think it was IDE mode


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## Rusuran (Oct 15, 2020)

Flaky said:


> Please check mentioned setting in bios or at least run AS SSD benchmark (it displays used driver, and it's enough to tell IDE/AHCI modes apart) and show results.
> Don't just leave us with unsolved mystery


Sorry, I completely missed your comment. I checked the BIOS setting and it was indeed in IDE mode. I changed it to AHCI and now numbers are where I think they should be (except for 840's seq write speed which is supposed to be around 410 but is 494 for some reason).
Thank you very much!


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