Review on 🔌 SI-PEX40142: 5-Slot M.2 B-Key SATA Base SSD Expansion Card with PCI-e 3.0 x2 Bandwidth, Requires x16 Slot by Patrick Martin

This review is for the dual slot version of the card with the ASMedia PCIe switching chip. I bought it hoping to get full NVMe performance on a Mac Pro 5.1. I found that the performance of this alleged x16 card is identical to the x8 card B07PRN2QCV Ableconn PEXM2-130 Dual PCIe NVMe M.2 SSDs Carrier Adapter Card - PCI Express 3.0 x8 Card Support 2X M.2 NGFF PCIe NVMe SSD for Mac and PC (ASMedia Switch ASM2824) - support for motherboards without branching. This meant I was getting around 2500MB/s on one SSD and 4000-4500MB/s on two at the same time. Pretty good, but less than what SSDs can actually do on a true 3rd gen PCIe bus. Since this card is advertised and physically looks like an x16 card, I expected more in the 3000-3500 MB/s range for an SSD and 6000-7000 MB / s for both at the same time. nope And I have confirmed that both NVMe drives can reach > 3000MB/s on another PCIe Gen3 machine. PCI slots. The other half of the PCIe slots are still there. In other words, the card is x16 physically, but really only x8 electrically. It sounds the other way around, but since only half of the PCIe electrical connections are routed anywhere on the board, it is. It works, just not as expected or advertised. The heatsink is fairly robust and has thermal interface material pre-applied in appropriate places with a protective film covering the material. I didn't use a heatsink for my tests because the Ableconn card I tested it with didn't have a heatsink either. I was arguing between 3 or 4 stars for the overall rating. I chose 3 because I specifically wanted this card because it was listed as PCIe x16 and is physically a PCIe x16 card, but it turned out to be PCIe x8 only. The intended use and what the description made me expect was the ability to use PCIe x16 Gen 2 with a Mac Pro -> ASMedia PCIe Chip -> 2x PCIe x4 Gen 3 NVMe. What it actually offers is a physical PCIe x16 connection -> PCIe x8 (Gen 2) electrical connection -> ASMedia PCIe chip -> 2x Gen3 PCIe x4 NVMe drives. Yes, it works, but the total available performance is halved and can be achieved with another card at a lower cost and without a physical x16 slot. Another point of interest for Mac Pro owners. The System Information report sees the card (actually two separate NVMe slots), but it reports connections as 8.0 GT (PCIe Gen 3), not 5.0 GT (PCIe Gen 2, which the Mac Pro really is). I wasn't expecting this, so I'm assuming it's reporting the information that the 3rd gen ASMedia chip is returning versus the NVMe slots. I personally will be returning this card and sticking with Ableconn as the performance is identical, it's cheaper and the smaller size is more flexible for use on other systems. I might try one of the 4 slot NVMe cards sometime in the future as they are true x16 cards just to see if they do the expected 6000-7000MB/s for 2 (or more) active drives deliver in a Mac Pro. Side Notes for other MacPro 4.1/5.1 owners: - Yes, it will boot on Mac Pro, you just need to follow the necessary firmware update steps to get it working. First is firmware update to High Sierra (10.13) which adds support for APFS boot, then firmware update to Mojave (10.14) which adds support for NVMe boot. You can actually use it with Sierra (10.12), but Sierra only works with NVMe drives running in 4kn mode (4k sectors). Most drives run in 512e mode (512-byte sector emulation) for compatibility reasons, but Sabrent offers a tool (Sabrent SSC) to switch their drives between 512e and 4kn operating modes. Sabrent SSC actually shows all NVMe drives, not just Sabrent drives. Since I had a Toshiba XG5 (not recommended!) that I was in the process of uninstalling, I decided to try the tool on it to see if it worked. If it blocked the drive, it wasn't much of a loss to me since I'd deleted it anyway. I tried using a tool on it, rebooted the system (required after switching operating mode) and confirmed that the disk is in 4kn mode. In other words, if you're not upgrading to Sierra like me and have access to Windows, it might be possible to switch other NVMe drives to 4kn mode for use with Sierra. Your mileage may vary, and note that changing the operating mode will completely erase the drive. Update: Changed from 3 to 4 stars because it works. I still think the ad text should be updated to not describe it as a x16 card as it isn't.