Are these speeds real Samsung Rapid Mode SSD 7531 MB/s Read and 7516 MB/s Write?

[Amigo1982]

Hello,
I wonder how is possible Samsung Magician and some other programs AS SSD Benchmark etc. to show more than 7000 MB/s read/write speed when my SATA cables and motherboard ports are limited to 600 MB/s - SATA 3.
Samsung 850 PRO 128GB in Rapid Mode, ASRock Z170 Gaming K6, 64GB DDR4, i7 7700k, Windows 10.

 

[TJ Hooker]

Because rapid mode uses some of your RAM as cache, so you're basically benchmarking your RAM rather than SSD.

 

[ShadyHamster]

Rapid mode creates a small partition with your system ram as a cache for the ssd, that's why you see those high speeds.

 

[Amigo1982]

Thank you for fast answer.
What will recommend - to use Samsung 960 EVO M.2 SSD with up to 3200 MB/s real Read speed, but not supported in Rapid mode or to keep Samsung 850 PRO in Rapid mode. For me it is doubtful this with Rapid mode and if i test again show different speed - it is not stable.

 

[Solandri]

IMHO RAPID mode is pretty worthless outside of generating jaw-dropping benchmarks. Windows (and every other modern OS) already uses free RAM as disk cache (there's no point leaving free RAM unused). The only difference is disk benchmark programs know to bypass Windows' cache when benchmarking. All RAPID mode does is shift RAM away from Windows' disk cache to its own disk cache.

Also, if you want my advice on SSDs, unless you're doing real-time video editing, ignore the sequential speeds. Get the SSD with the best 4k random read/write speeds. That's where SSDs are slowest, so that's what'll make the biggest noticeable difference. The drive takes more time doing its slowest operation, so a small improvement in its slowest op saves a lot of time. OTOH a fast operation is over in the blink of an eye, so making it twice as fast only makes it half a blink of an eye faster.

 

[USAFRet]

I ran my 500GB 850 EVO with RAPID mode for a while.
Huge benchmark numbers (like yours), no discernible user benefit.

So I turned it off.

That RAPID benchmark is mostly reading your RAM performance, not the actual drive.

 

[TJ Hooker]

In addition to what was said above, using rapid (or other RAM caching) increases your chances of data loss in case of power loss or other sudden PC shut off.