Question Weird Samsung 860 EVO 500GB SATA III behaviour

lfbb

Junior Member
Mar 16, 2020
4
0
11
I have 860 EVO 500GB Sata III and in my case the write speed drops down to ~300MB/s because the SLC cache fills up to 22GB and it won't flush, not even if I power my computer off, causing the SSD to write directly to the slower TLC memory.




I tried several times and I'm sure it is the SLC cache filling that's causing the poor write speeds. The weird thing in all off this is that if I go to BIOS and change any setting the SLC cache gets empty and I recover my speeds(~530MB/s sequential write). I know this is very strange but after changing some specific BIOS settings I came to the conclusion that any change would flush my SLC cache. Maybe the problem is a conflict between the SSD and the BIOS. I have an old MSI Z77A-G45 mobo with the lat est BIOS version, I can't do much about that. Here are my other specs:

Board: MSI Z77A-G45 | Bios: Version 2.13B1 | GPU: MSI GeForce GT 710 1GB | PSU: Corsair HX650 | CPU: Intel Core i7-3770 Ivy Bridge 3.4GHz (3.9GHz Turbo Boost) LGA 1155 77W | MEM: Kingston PC3-10700 1333Mhz 2x8GB | HDD: WD Caviar Black 1TB | SSD: Samsung 860 EVO 500GB SATA III | COOLER: Noctua NH-C12P SE14 | OC: (Turbo) 4.1Ghz 1.211 CPUV ram: 1333Mhz 1.5v | OS: Windows 10 Pro 64-bit v1809 build 17763.1098

Regards,

-lfbb
 

VirtualLarry

Lifer
Aug 25, 2001
48,150
5,007
126
I tried several times and I'm sure it is the SLC cache filling that's causing the poor write speeds. The weird thing in all off this is that if I go to BIOS and change any setting the SLC cache gets empty and I recover my speeds(~530MB/s sequential write). I know this is very strange but after changing some specific BIOS settings I came to the conclusion that any change would flush my SLC cache. Maybe the problem is a conflict between the SSD and the BIOS. I have an old MSI Z77A-G45 mobo with the lat est BIOS version, I can't do much about that. Here are my other specs:
It's probably not the settings change that's doing it, it's probably just that you're sitting at the BIOS, with NO DISK ACTIVITY, and thus, the SSD is able to do BACKGROUND TASKS, and "clean up" (flush) the SLC write cache, in that amount of time.
 

lfbb

Junior Member
Mar 16, 2020
4
0
11
Thanks for your post VirtualLarry.

It's probably not the settings change that's doing it, it's probably just that you're sitting at the BIOS, with NO DISK ACTIVITY, and thus, the SSD is able to do BACKGROUND TASKS, and "clean up" (flush) the SLC write cache, in that amount of time.
If I enter the BIOS and don't do any change the cache won't flush. If I save settings without changes the cache won't clear either. Is this an incompatibility with the BIOS or the SSD is faulty? It's still under warranty.

Regards,

-lfbb
 

VirtualLarry

Lifer
Aug 25, 2001
48,150
5,007
126
If I enter the BIOS and don't do any change the cache won't flush. If I save settings without changes the cache won't clear either. Is this an incompatibility with the BIOS or the SSD is faulty? It's still under warranty.
Hmm, that doesn't make any sense to me. Maybe someone else knows...
 

VirtualLarry

Lifer
Aug 25, 2001
48,150
5,007
126
Is there any software to clear the SLC Cache, like Intel SSD Toolbox has?
It's not meant to be long-term persistant, so much, as a temporary place to write to, until the SSD gets enough "background time" to write it out to the rest of the TLC/QLC drive portition. Generally, all it takes is a short time, without writing to the SSD, for it to get flushed. At least, that's the theory behind it.
 

pman6

Junior Member
Oct 10, 2011
11
0
66
It's weird. I have a new 860 evo 500gb, and I don't even see SLC cache speeds.

in CDM, it will benchmark at 500+MB/s write

but if I copy a 65gb iso file from my nvme drive to the 860, when I look at windows task manager, it immediately tops out at 440 MB/s and holds there until 30gb when it sinks to 360 MB/s


This is an empty drive.
My bench graph looks different from anandtech's.....

fdfdfsdfsfsdfsd.png

Where's my full speed slc cache?
If that is indeed the slc cache.... does that mean my slc cache is almost 135 GB?
 

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