Update () Hi and lucky day! I returned the Samsung EVO 250GB and ordered a from a local webshop. It said on their website that this drive is compatible for the 2009 Mac Mini. Of course all 6Gb drives 'work' but the negotiating speed is the culprit. When I installed the BX100 250GB I was disappointed because it also was set to 1.5Gb! I was on a chat with Crucial on their website and they suggested there must be something with 'garbage collection' and to fix it I should take out the drive and let it stay connected to power only (no data connection) for at least 8 hours and the drive would fix itself. This sounded like a crazy solution but ok, I will try it.
Jul 25, 2017 - Mac mini; Mini-DVI to DVI Adapter; 110W power adapter and power cord. One FireWire 800 port (up to 800 Mbps); Five USB 2.0 ports (up to 480 Mbps). 120GB, 250GB, or 320GB 5400-rpm Serial ATA hard disk drive4.
To my my amazement this really worked! Look at the enclosed pics.
I get at least twice the speed I had on 1.5Gb. So my conclusion is that Crucial SSD drives work with the NVidia SATA controller in the 2009 Mac Mini. I guess this should work also with other Crucial SSDs. Thanks @Dan for your suggestions. Sorry i did not accept your answer since I solved it myself.
From my experience the NVidia SATA controller is not easy to deal with. But that is what the 2009 Mac Mini has. I have no problems with 2008 MacBookPs and 6Gb SSDs. They all autosense capable speed. As it is hard nowadays to find any new 3Gb the conclusion here is that e.g. CRUCIAL SSDs work with the 2009 Mac Mini and NOT the Samsung EVO.
At least stay away from Sandforce driven SSDs. The trick with leaving the drive plugged into power-only for some hours is weird but works obviously! The 'problem' is Macs last too long. I doubt I would be plundering with a 2009 Dell laptop. This is a bit confusing:-( There are three SATA standards SATA I (1.5 Gb/s), SATA II (3.0 Gb/s) & SATA III (6.0 Gb/s). A SATA I system can only support a SATA I drive or a SATA II or SATA III drive which has been set to compatibility mode using a jumper (this also hold true with a SATA III drive in a SATA II system). Some newer drives have auto sense which allows them to match to the systems SATA ports speed.
SATA III drives when they first came out also had this compatibility jumper, as the need for running in the older systems lessened the jumper was pulled. So you can find drive that are fixed at either SATA II or SATA III and now drives that auto sense. Sadly, not all systems can support the auto sense drives like this one. No Dan, this is not confusing.
If you read this post: you will see that the problem is the Nvidia SATA controller, not the drive. From my experience I have used almost any 6Gb current drive on any old MacBook system.
All current 6 Gb drives (you can hardly find a 3Gb anymore) are autosensing. Seems there is something special going on with the Nvidia MCP79 (Mac Mini) not communicating with the drives controller (specially the Sandforce but also Samsung). The drive jumps back to its lowest possible speed which is 1.5Gb/s. Give me a few days and I hope to answer my own question with another SSD (Crucial).
I have not seen jumpers on 2.5' SATA drives in many years. OK, wasn't sure you followed things here on the SATA speeds. Correct the Nvidia controller has a problem running Auto sense drives. That was the point.
![Usb 3.0 Reader For Mac Mini A1283 Usb 3.0 Reader For Mac Mini A1283](https://jjbypc.com.au/654-thickbox_default/sabrent-usb-30-s-speed-4-slot-memory-card-reader-cf-mmc-sdxc-ms-pc-mac-cr-bmc3-.jpg)
You need a fixed speed drive and it can only be a SATA II drive. The drive you are pointed out here is a SATA III auto sense drive which won't work correctly.
As you have noted it drops down to SATA I which is what it is programed to do when it can't detect the SATA speed. And yes SSD drives don't have jumpers any more as they are auto sense. Different SSD manufactures do auto sense differently. Some just drop to the compatibility mode (SATA I) or test and link up with the systems SATA ports speed (which is in some ways the better unit). But no all SATA ports (via the North Bridge or Platform Controller) the system has play nice. Some like the MacBook Pro's won't allow the better auto sense drive link up as their clocks are slightly off.
So this is where the older fixed drives are needed and harder to find now. I just installed a 6 Gbps SATA III in my (running El Capitan) and was dismayed to find it operating at a negotiated link speed of 1.5 Gbps. I found a from 2012 on the Sandisk Forums isolating the issue to a finicky NVidia MCP79 SATA chipset on Macs of that era and suggesting going with other drive manufacturers; I also found that Sandisk had acknowledged the problem and had released a specifically for drives in Macs with the MCP79 chipset, albeit only for the Sandisk Extreme SSD. I figured I'd try the patch on the SSD Plus anyway (and return it to Amazon if it failed), so I burned the ISO to CD and tried to boot it off my external USB Panasonic DVD burner (the internal Superdrive has been dead for years). Unfortunately, the Linux system failed during bootup, so I rebooted to the SSD. To my surprise, I found the link operating at 3 Gbps.