It worked without a lot of fiddling. In my 30+ years of being a computer professional that is high praise, because so many computer add-ons don't. My only complaint and the reason I gave it four stars instead of five is that the drive setup configuration menu is not as intuitive as it should be and on my BIOS at least there was no way to get out of it except to reboot the computer. I wish I could have given 4 1/2 stars because that is really a minor problem in an otherwise excellent product.

Most Important: Online docs say don't plug in hard drives until card BIOS is configured or IT COULD WIPE OUT THE HARD DRIVE! This is NOT stated in the docs included with card. (2) Included docs say that BIOS utility is accessed during POST by pressing CTRL-M. THAT DOES NOT WORK! (3) No drives are recognized by the card. A card from a different manufacturer works fine in the same slot, so it is not a computer issue. (4) Tech Support is not accessible except by email. Been down that road too many times. It results in days or weeks of dialogue with 1st level techs that are typically clueless about their own products. That is not acceptable to me. In the future I will begin trying to reach tech support for a company BEFORE I buy their product and will no longer buy from a company that does not furnish live tech support. This is an ancient product by computer standards as the docs do not even mention Windows 10 compatibility, even though the Amazon listing says it is compatible.

Have a few of these and tossed them all out. Will freeze and will not boot if a drive is plugged in. After a bit of reserach I found out is because of the buggie marvel chip. So I got other controllers with non marvel chip and works perfectly fine. From what I read if you are using win 7 32 bit this will work for you but the chipset is so old it can't handle correctly any modern 64 bit os. Look else where, not worth your frustration.

A bit of background around my setup: I have a computer at home running VMWare ESXi, and on a (Windows Server 2012) VM I have Plex installed in order to stream content to various TVs and phones. I can make digital copies of movies and music and never again worry about the kids scratching disks or wearing out the Blueray optics on my PS4. I also back up all my family photos and videos to this VM, which allows me to stream this content as well, and I don't have to worry about my irreplaceable memories being lost when a phone dies. The missing piece, however, is that I don't want this (now over 2TB) collection of family memories to be lost if a hard drive crashes. I decided the stop-gap was to mirror the data between two hard drives (so I could lose one drive and still have my data), and then to regularly pull one of those disks out and replace it with another, to store it in a safe deposit box (so I could still have my data in the event that someone steals my server or the house burnt down). I tried Windows software RAID1 for awhile, and found it to be clunky, slow, and it sucked processing power from my CPU (which I'd rather have free for transcoding video). So the final answer was to get a card to handle hardware RAID.

Hardware RAID involves a separate processor which does nothing more than manage the reading and writing of data to/from your disks. Many SATA cards and motherboards (including the one in my server) claim to offer RAID, but there's no processor, so your CPU gets stuck with additional work managing your data. If you're looking for a good hardware RAID card, you're going to pay around $200. Then I found this (dedicated ARM processor, 4 physical ports, just over half a bill), and it seemed too good to be true. And it might be, still. But it's a whole lot of bang for the buck.

This card is not supported by ESXi, but it does work with (at least 5.5 and 6.0 in my experience) if you get this driver: https://www.v-front.de/2013/11/how-to-make-your-unsupported-sata-ahci.html. I have two RAID1 arrays: a pair of 8TB and a pair of 3TB; all Seagate drives. A third 8TB disk gets swapped in and the one that's replaced gets locked in a safe deposit box.

It does not display any message telling me when to press keys to get into the card's BIOS, so I had to look in the manual for the key combination, and I've found that if you start tapping Ctrl+M at one second intervals when you first start up, it will launch into the card's BIOS, and if you see the BIOS messages from the motherboard, then you need to reboot because you missed your window. The screen does go from black to a slightly bluish shade of black, presumably that's the window, but it's simpler to just button-mash until you're there. Also, if you have no drives plugged into the card, you don't get an opportunity to enter its BIOS. I wasted some time getting started because i wanted to see its BIOS to confirm it was working before plugging a disk in, and that's just an exercise in futility.

The interface is no-frills: you create an array and it gives you the status of the RAID. Because this card is unsupported by ESXi, this is the ONLY INTERFACE I have found so far. So if you want to view the SMART status of your drives or get email alerts on a potential disk failure, you probably need a more expensive, ESXi supported card. The controller card is a host device used locally by ESXi, so you cannot view the card in the Windows VM unless you tell ESXi to passthrough, and if you do that then you cannot use the array(s) as datastore(s) in ESXi. I am eventually going to tinker around with the Linux tools that come with the card; hopefully there is some mechanic that can work from the ESXi host and send alerts (I'll update this review if/when I know more).

The last issue I've had with this card, and why it might still be too-good-to-be-true: On occasion, and seemingly only when the disks would be seeing heavy write activity, everything just locks up. For example, I can move files from one virtual disk to another, while streaming video from Plex, while moving files to the VM via the network (CIFS), and the VM just locks up. RDP no longer allows inbound connections, and going to the console shows the time the lock-up happened frozen on the login screen; you cannot log in via console. If I attempt to restart the VM, the entire host becomes unresponsive, which leads me to beleive it's definitely a driver issue, although interestingly I'm able to interact with the host via vSphere and SSH terminal login just fine. But once this happens, I'm eventually going to have to power off or reboot the host via the physical buttons (which you typically don't EVER want to do). This may not happen for days at a time, but moving around lots of data (including heavy-disk-I/O tasks like compressing/uncompressing folders and defragmenting) is somewhat reliable in locking up the entire host. I have not yet been able to find logging in Windows or ESXi detailing what's happened here. Again, I'll update this if/when I'm able to learn more.

So, bottom line: a SATA controller card for this price seems crazy cheap. And it can be used with VMWare ESXi, using a third party driver set. It stops short of being a 5-star product because there's no way to get the status of your RAID without rebooting and sitting at a BIOS screen, and that feedback is pretty critical to having a RAID controller. And ultimately, it may be totally unfeasible for use in an ESXi host because it might be causing the entire host to need hard-powered off, but the jury is still out until I can prove it's this card at fault. I'll update this review if I come up with more info. Hope my experience helps others who are looking to do something similar, and maybe this will give you some ideas for your own setup.

Works well, no major issues; my only complaint is that I cannot get true 6Gbps/sec (about 750MB/sec) transfer on it, primarily because it's a 1x PCIe 2 card... the bus is maxed out around 500MB/sec. This should have been a 4x card.

Still, it works well, and supports my external RAID array with a performance I'm happy with.