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View Full Version : Raid 0 SSd low speed with g751



darknyght
03-29-2015, 12:43 AM
hey mates , i got these problem , well i installed two ssd Samsung evo and setup a raid 0 then installed windows files from
a retail windows CD i have and checked
read , write speed , seems i'm getting the speed as i would gotten it with one ssd however they both on raid 0 so whats is wrong into these


so any insight on these issue ?

joshindaphils
03-29-2015, 01:47 AM
The second bay only operates at SATA II speeds.

A striped array will only operate at roughly the multiple of the slowest drive.

Your single drive test was probably on the first bay and operating at SATA III speeds. You are using two drives, SATA II is roughly half the speed of SATA III therefor your perception is that the single and strip speeds are the same.

Hopefully there will be an update to get the second bay to SATA III until then enjoy the extra capacity of the second drive.

darknyght
03-29-2015, 02:19 AM
and i was scratching my head why it was not working probably after as i done everything correctly
well i didn't know the second bay run at speed of SATA II , i thought these laptop arrays runs at SATA III and asus still using SATA II on 2015 with gaming laptop :D?
that's kinda shock lol anyway thanks for lighting me up about these now i understand why its at such low speed the SATA II is bottelneck the SATA III so they both get down to SATA II speed which a shame i wanted to see the high speed
hope they update these , well if i can't enjoy the raid 0 speed it would be a risk for nothing i will just run them at AHCI until they issue update

hmscott
03-29-2015, 02:51 AM
and i was scratching my head why it was not working probably after as i done everything correctly
well i didn't know the second bay run at speed of SATA II , i thought these laptop arrays runs at SATA III and asus still using SATA II on 2015 with gaming laptop :D?
that's kinda shock lol anyway thanks for lighting me up about these now i understand why its at such low speed the SATA II is bottelneck the SATA III so they both get down to SATA II speed which a shame i wanted to see the high speed
hope they update these , well if i can't enjoy the raid 0 speed it would be a risk for nothing i will just run them at AHCI until they issue update

darknyght, does your laptop have an M.2 PCIE x4 connector in the Left Bay? It would be in the notched area at the top of the Bay. If so, that is the fastest storage interface you can use, much faster than SATA III, and with Gen 3 SSD's coming out soon - even faster than SATA III RAID0 x2.

The new Samsung SM951 and Plextor M7e are going to be faster than the current fastest M.2 PCIE x4, the Samsung XP941... so it is worth the wait if you can wait...

Samsung SM951 (512GB) PCIe SSD Review
http://www.anandtech.com/show/8979/samsung-sm951-512-gb-review

Plextor M7e M.2 PCIe SSD Performance Numbers From CES 2015
http://www.legitreviews.com/plextor-m7e-m-2-pcie-ssd-performance-numbers-ces-2015_156766

Those are known as Gen 3 drives, M.2 PCIE x4, up to 2150MB/sec Read and 1500MB/sec Write.

The XP941 is a Gen 2 M.2 PCIE x4, up to 1170MB/sec Read and 950MB/sec Write.

The M6e is slowest as a Gen 1 PCIE x2, up to 740MB/sec Read and 550MB/sec Write.

Also, you can pull out the 2.5" SSD from it's case and skip the caddy / M.2 mount plate and fit both drives in the Left Bay at the same time. This works for the short board 256GB 2.5" SSD's and the larger 512GB/1TB longer boards - you just need to finagle the mount for them.

When mounting both drives, use as little securing tape as possible, only strips across areas without RAM/controller parts. And, some have used additional adhesive heat sinks to wick off heat from the M.2 SSD under the 2.5" SSD.

How to add a 4th drive to your G751 - read the whole thread and look at the additional links and photo's to get ideas for mounting and heat transfer.
https://rog.asus.com/forum/showthread.php?58104-How-to-add-a-4th-drive-to-your-G751&highlight=plextor

It does suck that the Right Bay is only SATA II, but I doubt an update will fix it, there might not have been enough PCIE lanes to enable a 2nd SATA III port given the lanes dedicated to the new M.2 PCIE x4 slot.

Please come back and let us know what you work out :)