"From the makers of the MPX-3132, the mini PCIe card that gave eSATA to the (2006-2008) mac mini and iMac as seen on your site, there is also a USB 3.0 card.
(ref: articles here on 2006-08 Mac Mini eSATA (mini-PCIe) Install/Mod and (2009) iMac eSATA Mini PCIe Card Mod/Install - removing mini-PCIe Airport card and swapping in eSATA card + installing SIL3132 OS X drivers.-Mike)

(His mail had the eSATA card link (Commell's MPX-3132) used in the articles here, but I found a product page for their Mini-PCIe USB 3.0 card:
MPX-7202 - 2 x USB3.0 Mini PCIe card and MPX-7202 manual/datasheet, which has links to Windows drivers only. Datasheet notes an NEC controller.-Mike)

Has anyone had any luck with this mod? It would be especially nice since many adapters are available for converting an esata target to a USB 3.0 host.

First question is on support for the USB 3 chipset/OS X driver support. The datasheet lists an NEC controller (zooming in on a pix shows D720200F1) and IIRC some USB3 Macs use an NEC chip. (Although they're running OS X 10.8.x, later than even C2D upgraded 2006-2008 minis can use - but a 2009 iMac can run Mountain Lion.) Other things to consider are bus power and (as with the eSata card) - mods for the (external) Ports. The card kit includes a power adapter cable (but it's a molex 4pin) and a PCI bracket with 2 USB ports. (A reader that sent the iMac eSATA card mod photo gallery did a nice job modifying a PCI slot bracket's eSATA ports.)

Anyhow - I know it's a longshot (and for most not worth it), but If any readers have tried this mini-PCIe card (or some other brand/model) in a mod like this, let me know. Thanks.
(And I realize that even some onboard USB 3.0 Mac owners have had problems with USB3 interference w/BT and/or 2.4GHz WiFi.)
  

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