IDE vs AHCI vs RAID, MBR vs GPT, BIOS vs UEFI booting, and other topics

Kilobyte Kid

IDE vs AHCI vs RAID, MBR vs GPT, BIOS vs UEFI booting, and other topics

There seem to be some potentially important concepts involving settings or options on newer PCs that aren't covered in the very basic installation instructions found at  In fact, I've only seen them addressed at all in posts in the Knowledge Base.  It's not at all clear, though,. that these posts are necessarily authoritative and/or up-to-date given today's state of fairly rapidly evolving technology. 


Indeed, many customers won't even know that these are potential issues.  I am pretty technically savvy, but I'm no expert in this particular area, and I still had to do a lot of research on these topics to decide what were the optimum settings for a new SSD.  I can sort of understand that if a novice is just replacing a working HDD with an SSD, then simply cloning the HDD to the SSD and not changing any other BIOS or UEFI settings, then maybe most times these users will end up with usable systems.


But will those systems be optimum for an SSD?  Will they contribute to premature failure of the drive?  I've learned quite a lot recently by doing research... from sources outside of Crucial's KB.  For example, one of the things I have recently learned is that while several posts in the KB state to select the MBR partitioning scheme when cloning to the SSD, if you choose to perform a clean install of Windows 10 using Microsoft media, it automatically sets up GPT partitioning instead of MBR.  Is this a problem?  Well, not so far, at least.  But all I've seen in Crucial's KB thus far recommends using MBR only.  Why would that be when GPT seems far superior in many ways to MBR, especially for larger storage media?  It certainly seems to offer more flexibility, and it allows you to easily make use of wasted disk space caused by MBR's sometimes unallocated hidden partitions.


Another potential choice is IDE vs AHCI vs RAID.  What I've found is that if you set your drive configuration to RAID (which it already was on one system I was upgrading), then it uses AHCI as long as the drive isn't actually partitioned as a RAID drive.  But reading here in Crucial's KB, I've seen it stated that Crucial SSDs don't support RAID as such.  When I first saw that, I thought I needed to change the drive configuration to something besides RAID, but to what?  AHCI or Legacy (IDE)?  What I read elsewhere online is that AHCI was designed to offer speed advantages for drives using spinning disks, but theoretically won't help much for SSDs, and could actually contribute to premature failure.  True or False?  I don't really know, but I chose AHCI because... well, Crucial didn't tell me not to.


Similarly, some systems offer a choice between BIOS or UEFI boots.  Some of the OS installation media seems that it won't work if the drive it's on is booted in BIOS mode.  In fact, one article I read stated there is no way to install Windows 7 to a GPT drive that was booted in BIOS mode.  Boot it in UEFI mode and everything is fine.  How would I have known this was even an issue?


I think it's great to have essentially a set of installation instructions "For Dummies"; but I also believe it would be helpful to have a more expansive installation section for people like me who tend to overthink rather than underthink.