SSD Speed not even coming close to advertised speed 500mb/s

Jul 13, 2018
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I am transfering a game from one Sandisk 240GB to another Sandisk 240GB and it peaked at 300mb/s twice for 20 sec, the other 25 min it averaged 50-90MB/S. The game had 80GB total.

The SSDs are connected to a motherboard
LGA 1151 INTEL GIGABYTE GA-B150M-D3H MATX DDR4 2133MHZ CHIPSET B150 CROSSFIRE
The specs say it has 6 6gbps ports and 1 SATA Express port, the SSDs are connected to 2 of those 6 ports which I think are the SATA 3.0 port.

So what can I do to reach higher speeds? Or what explanation there is for this speed? Thanks guys!
 
*The best way to check your sustained disk performance IMO is to copy a large file (like a movie of say 6GB) between both drives and TIME it with a stop watch (don't assume Windows is accurate).

So let's say it took 13s and it was a 6.4GB file.

(6.4 x1024MB)/(13s) = 504MBps


That might be what you expect for a large file if both SSD's, the cables and the SSD controller are all rated for 6Gbps/SATA3 spec with say 500MBps+ or similar sustained reads/writes.

Other: I'm unclear if there's still any performance loss on some setups due to Specture/Meltdown patches. There was problems causing loss of SSD performance before.
https://www.techspot.com/article/1556-meltdown-and-spectre-cpu-performance-windows/

Probably NOT much of an issue and realistically should only be a few percent difference overall if it's even still an issue.
 

nobspls

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Mar 14, 2018
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SATA SSDs doing that is already pretty good. Where is it that they ever advertised 500mb/s sustained? It would be good to see that first. Usually there are many lawyer weasel words in those ads.
 
The 500 MB/s speeds are for sequential read/writes. e.g. If you're copying a multi-gigabyte movie file from one SSD to another. If you're copying games with a mix of large and small files, the speed will vary between about 30 MB/s (top small file read speed) to about 500 MB/s. Biased towards the low end because MB/s has seconds as the denominator, and the slower transfers take more seconds so dominate the average.

This is why I advise people to ignore the sequential speeds when shopping for a SSD. Get a SSD with decent (40+ MB/s) 4k read speeds. That'll make a much bigger difference (in time) than 500 MB/s vs 2 GB/s sequential speeds.
 
Download/install/run a Crystal DiskMark sequential test...

https://crystalmark.info/en/software/crystaldiskmark/

Actual transfers of lots of small files rarely blister along at peak transfer rates....; the 'brag-worthy' numbers usually apply to transfer of single larger files.
 
Jul 13, 2018
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Yeah, they advertised it as "530MB/s seq. read/write" and with * and ** marks. Those small letters say everything.
So yeah, they will rarely hit that cap I think. I will run that sequential test just for fun.
I will look if my cable is SATA 3 and definetely look on my next buy for one that is 40MB read write, which will probably be expensive hehe.
 
Jul 13, 2018
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For a moment (after 15 min non stop transfer) the speed dropped to 150kb/s.. lol
 
Lots of times its mega bits per sec being measured and it takes 8 bits to make a byte. And also it is the theoretical peak speed under perfect conditions and temps below freezing. It's called marketing but we just call it BS. It's more a way to compare drives then actual expected performance.
 


There are two SATA III cable types that come with most motherboards. SATA 3.0GB/s and SATA 6.0GB/s. Make sure you are using the SATA 6.0GB/s cable. It will say so on the cable itself. Or should anyway. SATA 3.0GB/s is perfectly fine for slower hard drives. All SSDs should be in SATA 6.0GB/s mode.

Also look at your motherboard's diagram layout in the manual and make sure you are using the 6.0GB/s ports. There will be fewer of those than the 3.0GB/s ports and they are colored differently. At least in my experience anyway with ASUS and MSI.
 

InvalidError

Titan
Moderator

I have never seen an HDD, SSD, thumb-drive or SD-card with achievable transfer rates specified in Mbps. The only place you'll see Mbps is in the interface speed which sets the burst speed limit and is of no importance when the media read/write speed is significantly lower.
 
For fun I tried FIVE DIFFERENT GAMES to copy between two Samsung SSD's.

My results varied quite a bit but as said file transfer speed drops significantly as file sizes go below a certain size.

*I overall averaged higher than 200MBps for all five games I tried peaking at times above 400MBps (including StarCraft 2) though one of the games dipped down to around 50MBps for several seconds (I assume lots of small files) so it's hard to say whether you have a problem or not.

The fact that you got above 300MBps sustained makes me think it's probably a non-issue.


*They've also tested various SSD's for game load times and discovered in general that there's usually very little benefit beyond a good SATA2 (not even SATA3) drive.


Some drives get severe slowdowns if you fill up the SSD cache but I suspect Sandisk doesn't make cheap desktop drives without sufficient cache.


Also, different benchmarks are NOT directly comparable. I've tried "AS-SSD", Samsung Magician and a couple others and they seem to vary quite a bit in how they report performance. I've never bothered to investigate that in detail.
 
*The best way to check your sustained disk performance IMO is to copy a large file (like a movie of say 6GB) between both drives and TIME it with a stop watch (don't assume Windows is accurate).

So let's say it took 13s and it was a 6.4GB file.

(6.4 x1024MB)/(13s) = 504MBps


That might be what you expect for a large file if both SSD's, the cables and the SSD controller are all rated for 6Gbps/SATA3 spec with say 500MBps+ or similar sustained reads/writes.

Other: I'm unclear if there's still any performance loss on some setups due to Specture/Meltdown patches. There was problems causing loss of SSD performance before.
https://www.techspot.com/article/1556-meltdown-and-spectre-cpu-performance-windows/

Probably NOT much of an issue and realistically should only be a few percent difference overall if it's even still an issue.
 

InvalidError

Titan
Moderator

3Gbps = SATA II, not SATA III.

That said, even cables from the SATA I (1.5Gbps) era will still work at 6Gbps as long as they're of sufficiently good quality to meet signal integrity requirements. I'm using an SATA cable from my P4's motherboard (SATA I) because my newer cables are too short to reach my SSD and I can't use their angled connectors where my SSD mount is. The link speed is indeed 6Gbps and the SMART status for SATA CRC errors is still zero 12 days after my most recent reboot. SATA doesn't care how old the cables are as long as they still meet specs for the speed you want to use.
 
Ah that's right. In any event, I was not able to reach my SSD's full speed unless using the 6GB/s port on the mobo and the 6GB/s cable. This was several years ago and a 4th generation Haswell build that I'm still using, so maybe things have changed. Or it was just the manufacturer (mine at the time was a Crucial SSD...currently running Samsung).
 
Time to upgrade to a 860 EVO 500GB, LOL!

 
Jul 13, 2018
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My SSD was basically empty, just with W10 OS in one of them and the other one only with the game to transfer. But I try to keep that 60-70% limit rate in mind.


Yes lol, I looked closer in the motherboard and this model doesn't have colors as they're all SATA3 and one express.
 
When you installed Windows did you only have the SSD connected you wanted it on, right? If you have multiple drives when you install windows it puts something on all of them and on boot up polls them which can slow your boot up.
 

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