20 Best Mac Pro Pcie Cards [2024]

Are you looking for the best Mac Pro Pcie Cards? Based on expert reviews, we ranked them. We've listed our top-ranked picks, including the top-selling Mac Pro Pcie Cards.

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# Preview Product
1 Mini 6-pin to 8-pin (6+2pins) Pci-e Video Card Power Cable for Mac Pro/g5 Mini 6-pin to 8-pin (6+2pins) Pci-e Video Card Power Cable for Mac Pro/g5
2 7-Port PCI-E to Type C (2), Type A (5) USB 3.0 Expansion Card with 2 Rear USB 3.0 Ports PCI Express... 7-Port PCI-E to Type C (2), Type A (5) USB 3.0 Expansion Card with 2 Rear USB 3.0 Ports PCI...
3 Sonnet Allegro Pro USB 3.2 Type A PCIe Card (Four SuperSpeed 10Gbps USB Connectors) Sonnet Allegro Pro USB 3.2 Type A PCIe Card (Four SuperSpeed 10Gbps USB Connectors)
4 COMeap Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro Tower / Power... COMeap Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro Tower /...
5 JacobsParts PCI Express Mini 6-pin to 6-pin PCI-e Video Card Power Cable for Apple Mac Pro Tower /... JacobsParts PCI Express Mini 6-pin to 6-pin PCI-e Video Card Power Cable for Apple Mac Pro Tower...
6 WiFi Card,Dual Band 2.4/5.8GHZ 300M Mini PCI-E WiFi Card,300Mbps Wireless Network Card,for Mac Pro... WiFi Card,Dual Band 2.4/5.8GHZ 300M Mini PCI-E WiFi Card,300Mbps Wireless Network Card,for Mac...
7 Sonnet Allegro USB 3.1, Two-Port USB-C 10Gb PCIe Card (USB3C-2PM-E) Sonnet Allegro USB 3.1, Two-Port USB-C 10Gb PCIe Card (USB3C-2PM-E)
8 TeamProfitcom Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Braided Sleeved Cable... TeamProfitcom Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Braided Sleeved Cable...
9 COMeap Mini 6 Pin to 6 Pin PCI Express Video Card Power Adapter Cable for Mac Pro G5... COMeap Mini 6 Pin to 6 Pin PCI Express Video Card Power Adapter Cable for Mac Pro G5...
10 Mini 6 Pin male to 8(6+2) Pin male PCI Express Video Card Power Adapter Cable for Mac Pro... Mini 6 Pin male to 8(6+2) Pin male PCI Express Video Card Power Adapter Cable for Mac Pro...
11 OWC Accelsior S PCIe Adapter for 2.5-inch SATA 6G Expansion Card Compatible with Mac Pro... OWC Accelsior S PCIe Adapter for 2.5-inch SATA 6G Expansion Card Compatible with Mac Pro...
12 Sintech NGFF M.2 nVME SSD Adapter Card for Upgrade 2013-2015 Year Macs(Not Fit Early 2013 MacBook... Sintech NGFF M.2 nVME SSD Adapter Card for Upgrade 2013-2015 Year Macs(Not Fit Early 2013 MacBook...
13 FebSmart 5X 10Gbps USB-A Ports PCIE USB 3.1 GEN2 Expansion Card for Windows 11, 10, 8.x,... FebSmart 5X 10Gbps USB-A Ports PCIE USB 3.1 GEN2 Expansion Card for Windows 11, 10, 8.x,...
14 NFHK PCI Express PCI-E 1X to 12+16Pin 2013-2017 Mac Pro Air SSD Convert Card for A1493 A1502 A1465... NFHK PCI Express PCI-E 1X to 12+16Pin 2013-2017 Mac Pro Air SSD Convert Card for A1493 A1502...
15 PCI-E to USB 3.0 Type C +3 Type A Expansion Card - Interface USB 3.0 4-Port Express Card Desktop... PCI-E to USB 3.0 Type C +3 Type A Expansion Card - Interface USB 3.0 4-Port Express Card Desktop...
16 OWC Accelsior 4M2 PCIe NVMe M.2 SSD Adapter Card Compatible with Mac Pro 2019, Mac Pro 2010-2012,... OWC Accelsior 4M2 PCIe NVMe M.2 SSD Adapter Card Compatible with Mac Pro 2019, Mac Pro 2010-2012,...
17 COMeap 16AWG Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro... COMeap 16AWG Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro...
18 Pack of 2 Mini 6 Pin to 6 Pin PCI Express Video Graphics Card Power Adapter Cable for Apple Mac Pro... Pack of 2 Mini 6 Pin to 6 Pin PCI Express Video Graphics Card Power Adapter Cable for Apple Mac...
19 2 Pcs Mini 6-pin to 6-pin Pci-e Video Card Power Cable for Mac Pro / G5 2 Pcs Mini 6-pin to 6-pin Pci-e Video Card Power Cable for Mac Pro / G5
20 COMeap Mini 6 Pin to 6 Pin PCI Express Video Card Power Adapter Braided Sleeved Cable for Mac Pro G5... COMeap Mini 6 Pin to 6 Pin PCI Express Video Card Power Adapter Braided Sleeved Cable for Mac Pro...
Bestseller No. 1
Mini 6-pin to 8-pin (6+2pins) Pci-e Video Card Power Cable for Mac Pro/g5
  • PCI-E PCIe PCI Express 6 pin Video Card Power Cable Adapter Converter for Mac Pro Dual Quad Core G5
  • Provide prower from internal logic board mini 6 Pin to PCI Express Vdieo Card standard 6 pin or 8 pin flexible
  • Works with any PCI Express-based MAC 2.0/2.3 Ghz Dual-Core or 2.5Ghz Quad-Core G5 and all Intel Mac Pro Tower machines or newer systems.
  • and any MAC video card with standard 6 pin or 8 pin power connectors such as but not limited to ATI Radeon 4870, 3870, 3850, 1900 GT/XT or any newer...
  • Real item is shown in the picture
Bestseller No. 2
7-Port PCI-E to Type C (2), Type A (5) USB 3.0 Expansion Card with 2 Rear USB 3.0 Ports PCI Express...
  • One Step Update your Computer to 7 ports USB3.0(2*Type C+5*Type A) Easily with PCI Express to USB3.0 Controller Adapter Card;
  • SuperSpeed USB 3.0 supports transfer rates of up to 5Gbps - The actual transmission speed is limited by the setting of the device connected.
  • Backwards compatible with USB 2.0 and 1.1 devices; Operating System Compatibility: Windows XP/Vista/7/8/10/MAC Pro 10.8.2 Above
  • With quick and easy installation, this USB 3.0 PCI express I/O Card offers a simple solution for connecting to and using USB 3.0 devices on your...
  • If the card doesn't work properly from the start, you may try out the following steps  Step 1: de- and reattach the devices to be recognized, so the...
Bestseller No. 3
Sonnet Allegro Pro USB 3.2 Type A PCIe Card (Four SuperSpeed 10Gbps USB Connectors)
  • SuperSpeed+ 10Gbps USB Ports—Adds four 10Gbps USB-A ports to your Mac Pro or Windows PC computer with PCIe slots; or Thunderbolt to PCIe card...
  • Dual USB 3.2 Gen 2 Controllers—Support data transfers at up to twice as fast as USB 3.0 and USB 3.1 Gen 1, and boost data transfer speeds between...
  • Powered Ports—Supports USB bus-powered SSD, SSD RAID, and hard drive devices with up to 7.5W power per port
  • Protected Power Delivery—Independent power regulation isolates each port to prevent cross-coupled power glitches that may cause accidental...
  • Mac, Windows 11+, and Linux Compatible. 2-year warranty and free lifetime customer support since 1986
Bestseller No. 4
COMeap Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro Tower / Power...
  • 『Dual Mini 6P - PCIe 8P』Dual mini 6 pin male end to plug into the Mac motherboard (NOTE: the end is mini 6 pin, not stanard 6 pin size.), PCIe 8...
  • 『Compatibility』ONLY compatible with Mac Pro, Power Mac G5 and all Mac Pro Models including: (1,1),(2,1),(3,1),(4,1),(5,1) or...
  • 『Connector』Connector A: 2x mini 6 pin male, Connector B: 1x 8 pin standard PCIe male;
  • 『Parameter』Gauge: 1007-18AWG (standard tin-coating copper wire), Length(including the connectors): 15-inch+15-inch(38cm+38cm), Rated power: 300W,...
  • 『Note』This cable was only designed for Mac Pro models as listed in the 2nd Point. Please check your PC type or contact us if you are not sure...
Bestseller No. 5
JacobsParts PCI Express Mini 6-pin to 6-pin PCI-e Video Card Power Cable for Apple Mac Pro Tower /...
  • Connectors: 6-pin Mini PCIe Power Male, 6-pin PCI-e Power Male
  • Length: 11.5 inches / 29cm (including connectors)
  • Wire: 18 AWG
SaleBestseller No. 6
WiFi Card,Dual Band 2.4/5.8GHZ 300M Mini PCI-E WiFi Card,300Mbps Wireless Network Card,for Mac Pro...
  • With 2.4 / 5.8GHZ dual frequency, 300Mbps wireless network card can provide a different experience
  • As long as it is HM65 or above chipset, it can be compatible
  • For Hackintosh driver-free, no driver required under for mac OS, plug and play
  • The WIFi card can support for XP, for WIN7, for WIN8, for WIN10, for MAC, etc.
  • Adopted of high quality electronic components, and accuracy process, ensure for the durability
Bestseller No. 7
Sonnet Allegro USB 3.1, Two-Port USB-C 10Gb PCIe Card (USB3C-2PM-E)
  • SuperSpeed+ USB Technology—Adds two 10Gbps USB-C (USB 3.2 Gen 2) ports to your Mac Pro with PCIe slots, Windows PC, Linux computer, or Thunderbolt...
  • Super-Powered Ports—Supports USB-C bus-powered SSD, SSD RAID, and hard drive devices with up to 15W (3.0A) power per port
  • Protected Ports—Independent power regulation isolates each port to prevent cross-coupled power glitches that may cause accidental disconnects
  • PCIe Data Link Auto-Negotiation—Card auto-negotiates one lane data link in a PCIe 3.0 slot and two lanes in a PCIe 2.0 slot, ensuring full 10Gbps...
  • Mac, Windows 11+, and Linux Compatible. 2-year warranty and free lifetime customer support since 1986
Bestseller No. 8
TeamProfitcom Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Braided Sleeved Cable...
  • Connector 1: standard GPU 8 Pin male . PCIe 8 pin male end to plug into the video graphics card - photo #2
  • Connector 2 : 2x mini 6 pin male ( not standard 6 pin male) !!! Dual mini 6 pin male end to plug into the Mac motherboard (NOTE: the end is mini 6...
  • Compatible with Power Mac G5 and all Mac Pro Models including: (1,1) - (5,1) or (2006) - (2012)
  • Connects a PCIe video graphics card with GPU 8 pin port to Mac motherboard with mini 6 pin port;
  • Length(Approx): 15-inches ; Gauge: standard 18AWG - UL1007;Color: Black; Rated power: 300W
Bestseller No. 9
COMeap Mini 6 Pin to 6 Pin PCI Express Video Card Power Adapter Cable for Mac Pro G5...
  • 『Mini 6P - Standard 6P』Mini 6 pin male end to plug into the Mac motherboard (NOTE: the end is mini 6 pin, not stanard 6 pin size.), Standard 6 pin...
  • 『Compatibility』Compatible with Mac Pro, Power Mac G5 and all Mac Pro Models including: (1,1),(2,1),(3,1),(4,1),(5,1) or...
  • 『Note』One end is Mini 6 pin male, the another end is 6 pin standard PCIe male. Please check the image 4th for details. This cable was only...
  • 『Note』This cable was only designed for Mac Pro models as listed in the 2nd Point. Please carefully check your PC type or contact us if you are not...
Bestseller No. 10
Mini 6 Pin male to 8(6+2) Pin male PCI Express Video Card Power Adapter Cable for Mac Pro...
  • Connector A: Mini 6 pin male (NOT standard 6 pin) ;Connector B: standard 8(6+2) pin PCIe male. Genuine new copper cores, no recycled materials;
  • Connects a PCIe video graphics card with 6 pin & 8 pin port to Apple motherboard with mini 6 pin port;
  • Compatible with any PCI Express-based MAC 2.0/2.3 Ghz Dual-Core or 2.5Ghz Quad-Core G5 and all Intel Mac Pro Tower ;
  • Only compatible with Mac Pro, Power Mac G5 and all Mac Pro Models including: (1,1 - 5,1) or (2006 - 2012);
  • Length:(Approx) 20 inches,Gauge: standard 18AWG - UL1007;Ribbon cable black .
Bestseller No. 11
OWC Accelsior S PCIe Adapter for 2.5-inch SATA 6G Expansion Card Compatible with Mac Pro...
  • Directly mount any standard 2.5-inch drive expansion to any PCIe x4 slot
  • Sustained speeds up to 550 MB/s
  • Enhance SATA 3G systems with SATA 6G support
  • Compatible With Mac Pro Mid 2006 - Mid 2012 (MacPro1,1 MacPro2,1 MacPro3,1 MacPro4,1 MacPro5,1) //Mac Pro and Mac Pro Rack Late 2019 (MacPro7,1) //...
  • 3 Year OWC Limited Warranty
Bestseller No. 12
Sintech NGFF M.2 nVME SSD Adapter Card for Upgrade 2013-2015 Year Macs(Not Fit Early 2013 MacBook...
  • Notice: Pls check which year is your macbook before buy this card. There is hibernation for all 2013-2014 Macs,you can set it to resolve this problem...
  • Support Adata NVMe SSD : SX6000, SX7000, SX8200, SX8200 Pro etc,Corsair : MP500, MP510,Crucial : P1,HP: ex920, ex950
  • Support Intel NVMe SSD : 600p, 660p, 760p,Toshiba XG3-XG4-XG5-XG5p-XG6 line,Samsung: 960 Evo, 960 Pro, 970 Evo, 970 Pro,WD:v1, v2 and v3,MyDigital:...
  • NOT Support: PM981,950 Pro,WD Blue NvME SN570 /SN770
  • Notice:It can't support recovering from internet,important to prepare bootable USB disk driver(M.2 PCIe has no OS systerm inside,it must be erased...
Bestseller No. 13
FebSmart 5X 10Gbps USB-A Ports PCIE USB 3.1 GEN2 Expansion Card for Windows 11, 10, 8.x,...
  • 1. FebSmart FS-A5-Pro will allow users add 5X 10Gbps USB 3.1 GEN2 type A ports on Desktop PCs, MAC Pros and Working Stations for large data transfers....
  • 2. Built in FebSmart Self-Powered Technology. No need to plug any power cables from PCs power supply unit, but each USB 3.1GEN2 port can get 5V/3A...
  • 3. Based on ASMedia ASM3142 the 3rd generation USB 3.1 GEN2 16Gbps host controller and the latest VIALab VL822 USB 3.1 GEN2 10Gbps hub controller....
  • 4. Compatible System: 1. Plug and Play on Windows 11, 10, 8.x (32/64bit) and Windows Server 2012, 2012R2, 2016, 2019, 2022. 2. Need to install driver...
  • 5. ATTENTION: 1. PCIE X4 interface design, will compatible with PCIE X4, X8, X16 slot, NOT works on PCIE X1, X2 slot. 2. Please use this PCIE USB card...
Bestseller No. 14
NFHK PCI Express PCI-E 1X to 12+16Pin 2013-2017 Mac Pro Air SSD Convert Card for A1493 A1502 A1465...
  • With Standard PCI Back Bracket
  • Single-lane (x1) PCI Express throughput rates up to 5 Gbps
  • Support Windows 10 or later
  • The SSD is not included.
  • PCI Express PCI-E 1X to 12+16Pin 2013-2017 Mac Pro Air SSD Convert Card for A1493 A1502 A1465 A1466
Bestseller No. 15
PCI-E to USB 3.0 Type C +3 Type A Expansion Card - Interface USB 3.0 4-Port Express Card Desktop...
  • No Power connection required,built-in power IC
  • Backwards compatible with USB 2.0 and 1.1 devices; Operating System Compatibility: Windows XP/Vista/7/8/10/MAC Pro 10.8.2 Above and Linux
  • Compatible with PCIE X1, X4,X8, X16 slot
  • Come with Low profile Bracket ,compatible with Slim PC
  • If the card doesn't work properly from the start, you may try out the following steps Step 1: de- and reattach the devices to be recognized, so the...
Bestseller No. 16
OWC Accelsior 4M2 PCIe NVMe M.2 SSD Adapter Card Compatible with Mac Pro 2019, Mac Pro 2010-2012,...
  • Work faster: over 6,000MB/s real-world speed in RAID 0 with capacity for critical footage, images, files, and games
  • Highly versatile: installs into a full-height, half-length x8 or x16 PCIe 3.0 or 2.0 slot
  • Includes SoftRAID: robust software for creating, monitoring, and managing advanced RAID sets
  • Compatible With Mac Pro Mid 2010- Mid 2012 (MacPro5,1) // Mac Pro and Mac Pro Rack Late 2019 (MacPro7,1) // PC Towers
  • 3 Year OWC Limited Warranty
Bestseller No. 17
COMeap 16AWG Dual Mini 6 Pin to 8 Pin PCI Express Video Card Power Adapter Cable for Mac Pro...
  • 『Dual Mini 6P - PCIe 8P』Dual mini 6 pin male end to plug into the Mac motherboard (NOTE: the end is mini 6 pin, not stanard 6 pin size.), PCIe 8...
  • 『Compatibility』Compatible with Mac Pro, Power Mac G5 and all Mac Pro Models including: (1,1),(2,1),(3,1),(4,1),(5,1) or...
  • 『Connector』Connector A: 2x mini 6 pin male, Connector B: 1x 8 pin standard PCIe male;
  • 『Parameter』Gauge: 1007-16AWG (standard tin-coating copper wire)(NOTE:The load current of 16AWG cable is up to 10A. That of 18AWG is 6.5A.),...
  • 『Note』This cable was only designed for Mac Pro models as listed in the 2nd Point. Please check your PC type or contact us if you are not sure...
Bestseller No. 18
Pack of 2 Mini 6 Pin to 6 Pin PCI Express Video Graphics Card Power Adapter Cable for Apple Mac Pro...
  • Length:14'' inch(35cm), Gauge: 18AWG
  • Connectors: mini 6 pin male, 6 pin standard PCIe male
  • Fit PCI Express-based MAC 2.0/2.3 Ghz
  • Dual-Core or 2.5Ghz Quad-Core G5 and all Intel Mac Pro Tower machines
  • Package Contents: 2 x Mini 6 Pin to 6 Pin Power Adapter Cable
Bestseller No. 19
2 Pcs Mini 6-pin to 6-pin Pci-e Video Card Power Cable for Mac Pro / G5
  • PCI-E PCI Express 6 pin Video Card Power Cable for Mac Pro Dual Quad Core G5 or later model
  • Works with any MAC video card with 6 pin power connectors
  • High Quality Cables
Bestseller No. 20
COMeap Mini 6 Pin to 6 Pin PCI Express Video Card Power Adapter Braided Sleeved Cable for Mac Pro G5...
  • 『Mini 6P - Standard 6P』Mini 6 pin male end to plug into the Mac motherboard (NOTE: the end is mini 6 pin, not stanard 6 pin size.), Standard 6 pin...
  • 『Compatibility』Compatible with Mac Pro, Power Mac G5 and all Mac Pro Models including: (1,1),(2,1),(3,1),(4,1),(5,1) or...
  • 『Note』One end is Mini 6 pin male, the another end is 6 pin standard PCIe male. Please check the image 4th for details;
  • 『Note』One end is Mini 6 pin male, the another end is 6 pin standard PCIe male. Please check the image 4th for details. This cable was only...
  • 『Parameter』Gauge: 1007-18AWG with braided sleeves for easy cable management(standard tin-coating copper wire), Length: 14-inch(35cm), Rated power:...

Having trouble finding a great Mac Pro Pcie Cards?

This problem is well understood by us because we have gone through the entire Mac Pro Pcie Cards research process ourselves, which is why we have put together a comprehensive list of the best Mac Pro Pcie Cardss available in the market today.

After hours of searching and using all the models on the market, we have found the best Mac Pro Pcie Cards for 2023. See our ranking below!

How Do You Buy The Best Mac Pro Pcie Cards?

Do you get stressed out thinking about shopping for a great Mac Pro Pcie Cards? Do doubts keep creeping into your mind?

We understand, because we’ve already gone through the whole process of researching Mac Pro Pcie Cards, which is why we have assembled a comprehensive list of the greatest Mac Pro Pcie Cards available in the current market. We’ve also come up with a list of questions that you probably have yourself.

John Harvards has done the best we can with our thoughts and recommendations, but it’s still crucial that you do thorough research on your own for Mac Pro Pcie Cards that you consider buying. Your questions might include the following:

  • Is it worth buying an Mac Pro Pcie Cards?
  • What benefits are there with buying an Mac Pro Pcie Cards?
  • What factors deserve consideration when shopping for an effective Mac Pro Pcie Cards?
  • Why is it crucial to invest in any Mac Pro Pcie Cards, much less the best one?
  • Which Mac Pro Pcie Cards are good in the current market?
  • Where can you find information like this about Mac Pro Pcie Cards?

We’re convinced that you likely have far more questions than just these regarding Mac Pro Pcie Cards, and the only real way to satisfy your need for knowledge is to get information from as many reputable online sources as you possibly can.

Potential sources can include buying guides for Mac Pro Pcie Cards, rating websites, word-of-mouth testimonials, online forums, and product reviews. Thorough and mindful research is crucial to making sure you get your hands on the best-possible Mac Pro Pcie Cards. Make sure that you are only using trustworthy and credible websites and sources.

John Harvards provides an Mac Pro Pcie Cards buying guide, and the information is totally objective and authentic. We employ both AI and big data in proofreading the collected information.

How did we create this buying guide? We did it using a custom-created selection of algorithms that lets us manifest a top-10 list of the best available Mac Pro Pcie Cards currently available on the market.

This technology we use to assemble our list depends on a variety of factors, including but not limited to the following:

  1. Brand Value: Every brand of Mac Pro Pcie Cards has a value all its own. Most brands offer some sort of unique selling proposition that’s supposed to bring something different to the table than their competitors.
  2. Features: What bells and whistles matter for an Mac Pro Pcie Cards?
  3. Specifications: How powerful they are can be measured.
  4. Product Value: This simply is how much bang for the buck you get from your Mac Pro Pcie Cards.
  5. Customer Ratings: Number ratings grade Mac Pro Pcie Cards objectively.
  6. Customer Reviews: Closely related to ratings, these paragraphs give you first-hand and detailed information from real-world users about their Mac Pro Pcie Cards.
  7. Product Quality: You don’t always get what you pay for with an Mac Pro Pcie Cards, sometimes less, and sometimes more.
  8. Product Reliability: How sturdy and durable an Mac Pro Pcie Cards is should be an indication of how long it will work out for you.

John Harvards always remembers that maintaining Mac Pro Pcie Cards information to stay current is a top priority, which is why we are constantly updating our websites. Learn more about us using online sources.

If you think that anything we present here regarding Mac Pro Pcie Cards is irrelevant, incorrect, misleading, or erroneous, then please let us know promptly!

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FAQ:

Q: Which Mac Pro models support PCIe (PCI Express)?

A: All Mac Pro models support PCIe (PCI Express) cards, but the type of cards supported varies, particularly between early and later systems. The installation procedure varies, too.

Q: Where do I put a PCIe card on a Mac Pro 1?

A: I’d rather install your PCIe controller card on the top slot (slot 4) of your MacPro1,1, which is x8 by default. Anyway, you can change your PCIe lane allocation using the application /System/Library/CoreServices/Expansion Slot Utility.

Q: How many PCIe slots does the 2019 Mac Pro have?

A: The Mac Pro introduced in 2019 has eight PCIe slots: 1 Four double-wide slots 2 Three single-wide slots 3 One half-length slot preconfigured with the Apple I/O card

Q: Is there anyway to reset the PCIe configuration for Mac Pro?

A: Is anyway to reset PCIe configuration and configured again for MAC PRO. I’d rather install your PCIe controller card on the top slot (slot 4) of your MacPro1,1, which is x8 by default. Anyway, you can change your PCIe lane allocation using the application /System/Library/CoreServices/Expansion Slot Utility.