AHCI ? When you have one SED drive

I understand you have to change the Bios to emulate AHCI if you have an SED such as the Samsung 850 Evo.
The main drive will be an HP SSD, and I dont know if this is an SED? The secondry drive will be an Intel 750, which is PCIe based NVME. ( I assume this is not a SED ).

HP warns not to change the SATA controller emulation after loading the OS.that seemed a little strange. They say it can cause problems.

All this is a bit beyond me.

I guess I was wondering - does one, i.e. can one in Win7 Pro, set the SATA emulation seperately for each individual controller for each separate drive?.


Or can I not mix SED drives and non SED drives in the same box?

Or does this not apply for PCIe NVME based cards such as the Intel 750?

Any help of links to where this is all explained much appreciated.

Most BIOS will have three settings for the Storage Controller, AHCI, RAID and IDE. Unless you plan to run a software RAID of some sort it should be set to AHCI. The IDE setting is mainly for legacy operating systems that are not SATA aware. This needs to be set before the operating system is installed, otherwise it will likely cause the operating system to crash while loading. There are tutorials on how to change it after the operating system has been installed, it involves editing the Registry.

In your case it should be set to AHCI.

-dave-m- wrote in post #17620293
Most BIOS will have three settings for the Storage Controller, AHCI, RAID and IDE. Unless you plan to run a software RAID of some sort it should be set to AHCI. The IDE setting is mainly for legacy operating systems that are not SATA aware. This needs to be set before the operating system is installed, otherwise it will likely cause the operating system to crash while loading. There are tutorials on how to change it after the operating system has been installed, it involves editing the Registry.

In your case it should be set to AHCI.

Thanks, Yes it says:-
"SATA Emulation Modes
The SATA and sSATA controllers are capable of being set to three different SATA emulation modes. Separate controls are provided for SATA Emulation Mode in the BIOS under Advanced > Device Configurations > SATA Emulation Mode and Advanced > Device Configurations > sSATA Emulation Mode.
• RAID1 (Default; ACHI + RAID capability with greatest flexibility for most users)
• AHCI (Required when using SEDs)
• IDE (Legacy mode, limited functionality - Not recommended)"

I was just worried how the standard HP 256GB SSD would play as I discovered its not SED. I assume the Intel 750 wont be effected by how the SATA controller is set as it is PCI e.

I've never heard of SED. If you have old Windows 7 just put the SSD in under whatever mode you like, it will work. If you reinstall the OS set the BIOS to AHCI before you do the install. You can switch W7 to AHCI from IDE, it's just a driver.

W10 is a free upgrade in 4-6 weeks, you'll want that on AHCI.

tim wrote in post #17620696
I've never heard of SED. If you have old Windows 7 just put the SSD in under whatever mode you like, it will work. If you reinstall the OS set the BIOS to AHCI before you do the install. You can switch W7 to AHCI from IDE, it's just a driver.

W10 is a free upgrade in 4-6 weeks, you'll want that on AHCI.

SED is a self encrypting drive, encryption/decryption is all handled within the drive by the controller chip, once a password is set the drive handles everything else. It's actually fairly common, yet very few people know about it or use it. For Samsung SSD's that support it, it can be setup within the Magician Software.

-dave-m- wrote in post #17620755
SED is a self encrypting drive, encryption/decryption is all handled within the drive by the controller chip, once a password is set the drive handles everything else. It's actually fairly common, yet very few people know about it or use it. For Samsung SSD's that support it, it can be setup within the Magician Software.

Thanks for the perfect reply, they ( including Samsung ) say it has an enourmous speed increase, how true that is ??

Encryption slows things down compared with a standard unencrypted drive, though hardware accelerated it probably doesn't hurt much. I don't know why you'd use it though, for a personal computer. If your drive gets stolen, so what? I don't really care if all my data is stolen, there's nothing on my computers that sensitive, even my financials.

I'm fairly familiar with security. I design fairly large computer software systems as my day job, for individuals medical information. That's encrypted end to end, for information in transit and at rest. I have encrypted information on my PC for things I consider critical, but even most of my financials are stored unencrypted. Encryption carries risk of data loss and performance penalty. If your computer fails and you have to move it to another drive can you access it? Do you have to enter a password somewhere? If not then I see no benefit, and if you do there's some risk.

Then again, if you want it, why not. Keep unencrypted backups.

SED must be supported by the motherboard and BIOS, you have to enter a password if it is enabled. You can remove the drive and access the data from any other PC as long as that PC's motherboard and BIOS support SED.

Personally I do not use it or feel a need to use it. I do not keep any sensitive data on my PC's or Laptop. I really don't see any need to use it on a home PC.

-dave-m- wrote in post #17620854
SED must be supported by the motherboard and BIOS, you have to enter a password if it is enabled. You can remove the drive and access the data from any other PC as long as that PC's motherboard and BIOS support SED.

Personally I do not use it or feel a need to use it. I do not keep any sensitive data on my PC's or Laptop. I really don't see any need to use it on a home PC.

Likewise I have no need for encryption at all - I had read that it made the disc faster?
Maybe they meant quicker than if one used software encryption.
My only interest is the Samsung 850 Evo is a good brand and fast for the money. If it was just as quick without encryption enabled, my would not be enabled. Really can domwithout another password to fill in.

Encryption is highly unlikely to make anything faster, it's very likely to slow things down.

Also, switch to AHCI when you go to W10. W10 is better than W7.

tim wrote in post #17621104
Encryption is highly unlikely to make anything faster, it's very likely to slow things down.

Also, switch to AHCI when you go to W10. W10 is better than W7.

Thats what I thought , especially as in the old days encryption really slowed things down.
I must have misunderstood that article - maybe they ment SEDs were much faster than software encryption. I took it that with or without encryption enabled it made this SSD faster.

But interestingly the Intel 750, which is the fastest affordable drive I can find is not a SED.