Are all the pci-e slots full x16?

Yes, But 2x full size video cards are going to cover 2 of the slots..

Does this mean all PCI-E slots can be used and still be able to use the M2 slots? * The M2_2 default setting is CPU lane. However, when a PCIe expansion card is installed in the PCI_E2 slot, the M2_2 will be automatically switched to PCH lane. * The SATA2 connector will be unavailable when M2_2 uses PCH lanes and a M.2 SATA SSD is installed in the M2_2 slot.

No, all PCI-E slots cannot be used simultaneously with both M2 slots. Specifically, if a PCIe expansion card is installed in the PCI_E2 slot, the M2_2 slot will switch to PCH lane, which causes the SATA2 connector to be unavailable if an M.2 SATA SSD is installed in the M2_2 slot.

Does this board have a slot for more boom sound for headphone use?

Yes, the motherboard has Audio Boost 4, which rewards your ears with studio grade sound quality.

The screws holes for the CPU fan don’t go all the way through to the other side like most other mother boards. How do I find a compatible CPU fan? Any recommendations?

Just be sure that the CPU cooler that you choose is compatible with LGA 2066. LGA 2066 boards already have a backing plate mounted.

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MSI PRO X299 PRO LGA 2066 Intel X299 ATX Intel Motherboard

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Option: X299 PRO

MEG X299 CREATION
X299 GAMING PRO CARBON
X299 PRO
X299M-A PRO

Intel X299
Supports Intel Core X-series 10000/9000/78xx (above) processors for socket LGA2066
Supports DDR4 4200+(OC)/ 4000(OC)/ 3800(OC)/ 3733(OC)/ 3600(OC)/ 3466(OC)/ 3400(OC)/ 3333(OC)/ 3300(OC)/ 3200(OC)/ 3000(OC)/ 2933/ 2666/ 2400/ 2133 MHz

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Specs

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Learn more about the MSI X299 PRO

Model
Brand	MSI
Series	PRO
Model	X299 PRO

Supported CPU
CPU Socket Type	LGA 2066
CPU Type	Supports Intel Core X-series 10000/9000/78xx (above) processors for socket LGA2066

Chipsets
Chipset	Intel X299

Onboard Video
Onboard Video Chipset	None

Memory
Number of Memory Slots	8x288pin (DDR4)
Memory Standard	Supports DDR4 4200+(OC)/ 4000(OC)/ 3800(OC)/ 3733(OC)/ 3600(OC)/ 3466(OC)/ 3400(OC)/ 3333(OC)/ 3300(OC)/ 3200(OC)/ 3000(OC)/ 2933/ 2666/ 2400/ 2133 MHz * For the latest information about memory, please visit http://www.msi.com
Maximum Memory Supported	256GB
Channel Supported	Quad Channel

Expansion Slots
PCI Express 3.0 x16	4 x PCIe 3.0 x16 slots Support x16/x8/x16/x8 mode with the 48-lane CPU. Support x16/x4/x16/x8 mode with the 44-lane CPU. Support x16/x4/x8/x0 mode with the 28-lane CPU.

Storage Devices
Serial ATA (SATA)	6 x SATA 6Gb/s ports * The SATA1 connector will be unavailable when a SATA M.2 SSD has been installed in the M2_1 slot.
M.2	2 x M.2 slot (Key M) Support up to PCIe 3.0 x4 and SATA 6Gb/s, 2242/2260/2280/22110 storage devices* * The M2_2 default setting is CPU lane. However, when a PCIe expansion card is installed in the PCI_E2 slot, the M2_2 will be automatically switched to PCH lane. * The SATA2 connector will be unavailable when M2_2 uses PCH lanes and a M.2 SATA SSD is installed in the M2_2 slot.
Intel Optane Ready	Intel Optane Memory Ready* * M2_2 supports Intel Optane Memory by switching to PCH lanes.
SATA RAID	0/1/5/10

Onboard Audio
Audio Chipset	Realtek ALC1220
Audio Channels	7.1-Channel High Definition Audio Supports S/PDIF output

Onboard LAN
LAN Chipset	Realtek RTL8125-CG
Second LAN Chipset	Intel I219V * I219 LAN doesn't support G3 to S5 Wake
Max LAN Speed	2.5Gbps + 1Gbps

Rear Panel Ports
Back I/O Ports	1 x Optical S/PDIF Out / 1 x PS/2 Keyboard/Mouse Combo / 1 x USB 3.2 Gen 2x2 Type-C / 2 x LAN (RJ45) / 4 x USB 2.0/1.1 / 4 x USB 3.2 Gen 1 Type-A / 5 x Audio Jacks

Internal I/O Connectors
Onboard USB	2 x USB 2.0 connectors (supports additional 4 USB 2.0 ports) 2 x USB 3.2 Gen1 connectors (supports additional 4 USB 3.2 Gen1 ports) 1 x USB 3.2 Gen2 Type-C port
Other Connectors	1 x 4-pin CPU fan connector 1 x 4-pin Water Pump connector 4 x 4-pin system fan connectors 1 x Front panel audio connector 2 x System panel connectors 1 x TPM module connector 1 x Chassis Intrusion connector 1 x Virtual RAID on CPU connector 1 x Thunderbolt Add-on Card Connector

Physical Spec
Form Factor	ATX
Dimensions (W x L)	12.0" x 9.6"
Power Pin	1 x 24-pin ATX main power connector 2 x 8-pin ATX 12V power connectors

Features
Features	Supports Intel Core X-series Processors 10000/9000/78xx (above) series for LGA2066 Socket. Supports DDR4 Memory, 8 DIMMs, Quad Channel Max Frequency DDR4-4200+(OC). Lightning USB 20G: Powered by ASMedia ASM3242 USB 3.2 Gen2x2 controller, offers the fastest USB speeds with stability. Twin Turbo M.2: Running at PCI-E Gen3 x4 maximizes performance for NVMe based SSDs. Set Core Power Free: Core Boost, 2x8-pin CPU power connector, Core Boost, DDR4 Boost. Extended Heatsink Design: MSI extended PWM and enhanced circuit design ensures even high-end processors to run in full speed. Dual LAN: Premium network solution included 1 x 2.5G LAN for professional and multimedia use. Delivers a secure, stable and fast network connection. Audio Boost 4: Reward your ears with studio grade sound quality. Multi-GPU: With Steel armor PCI-E slots. Supports 3-Way SLI / Crossfire.

Additional Information
First Listed on Newegg	August 14, 2026

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The MSI PRO X299 PRO is an ATX workstation motherboard for Intel Core X-series processors using the LGA 2066 socket. It suits high-performance desktop builders who need quad-channel DDR4 memory, up to 256GB of RAM, four PCIe 3.0 x16 slots, dual LAN, and multi-drive storage support.

Spec Summary

Attribute	Value
Best For	LGA 2066 workstation and enthusiast desktop builds using Intel Core X-series processors, quad-channel DDR4 memory, multiple PCIe graphics or expansion cards, and high-speed NVMe storage
Processor And Platform	Intel X299 platform with an LGA 2066 socket for Intel Core X-series 10000, 9000, and 78xx-or-higher processors; no onboard video chipset
Memory Configuration	Eight 288-pin DDR4 DIMM slots support up to 256GB in quad-channel mode, with speeds up to DDR4-4200+ through overclocking
Expansion And Multi-GPU	Four PCIe 3.0 x16 slots support lane configurations based on the installed CPU, with support for up to three-way SLI or CrossFire
Storage And RAID	Six SATA 6Gb/s ports and two Key M.2 slots support PCIe 3.0 x4 or SATA 6Gb/s drives in 2242, 2260, 2280, and 22110 sizes; SATA RAID supports 0, 1, 5, and 10, with Intel Optane Memory support through M2_2 PCH-lane configuration
Wired Networking	Dual Ethernet includes Realtek 2.5Gbps and Intel 1Gbps controllers, with two rear RJ45 ports
Audio Setup	Realtek ALC1220 7.1-channel high-definition audio with five rear audio jacks and optical S/PDIF output
Rear I/O And USB	Rear connectivity includes one USB 3.2 Gen 2x2 Type-C port, four USB 3.2 Gen 1 Type-A ports, four USB 2.0/1.1 ports, dual RJ45 Ethernet, a PS/2 combo port, optical S/PDIF, and five audio jacks
Internal Headers And Cooling	Internal connectivity provides USB 2.0 and USB 3.2 Gen 1 expansion headers, an additional USB 3.2 Gen 2 Type-C header, CPU, pump, and system fan connectors, plus TPM, Thunderbolt add-on card, front-audio, system-panel, chassis-intrusion, and virtual RAID on CPU connectors
Power And Form Factor	ATX motherboard measuring 12.0 x 9.6 inches with a 24-pin main ATX connector and two 8-pin ATX 12V CPU power connectors
Model Identifiers	MSI PRO X299 PRO motherboard, model X299 PRO

Item#: 9SIC6E1M4K6973