Asus Prime X299- A II ATX Motherboard (Intel X299) LGA 2066, 12 IR3555 Power Stages, DDR4 4266 MHz, Triple M.2, USB 3.2 Gen 2 Type-C, Intel LAN and Aura Sync RGB Lighting
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AI Verdict
This is a stable foundation for an Intel Core X-Series workstation, but you have to be willing to wrestle with Asus's buggy RGB and fan software to get there.
The 12 IR3555 power stages and 44 PCIe lanes provide massive bandwidth for multi-GPU rendering setups. The software side is a mess, requiring you to bypass Aura Sync and Fan Xpert to avoid daily crashes.
If you need flawless RGB integration and software fan control, look for a board with Corsair iCUE integration or rely on a dedicated hardware fan controller.
Regret Score™
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Issues discovered after purchase
Critically weak dimension
Amazon rating vs actual quality
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Pros
- 12 IR3555 power stages keep VRM temperatures well under control even when pushing a 7800X to 4.45GHz at 1.055V.
- Supports up to 256GB of quad-channel DDR4 memory with stable traces for 4266 MHz overclocks.
- Three M.2 slots include thick aluminum heatsinks that drop sustained NVMe SSD temperatures by up to 20°C.
- Splits 44 PCIe lanes into a true x16/x16/x8 configuration for multi-GPU rendering or deep learning rigs.
Cons
- The Aura Sync software frequently fails to recognize advertised compatible RGB components like Corsair Vengeance RAM.
- Fan Xpert 4 cannot actually pull temperature data from your GPU sensors despite Asus marketing materials showing it can.
- The I/O shield Prime logo LED stays illuminated even when the PC is fully shut down in the S5 state.
- The plastic protective film on the heatsink housing tears easily and leaves frustrating plastic bits stuck in the corners.
Dimension Scores
12 IR3555 power stages and ProCool II connectors easily handle 165W TDP chips without thermal throttling.
Triple M.2 slots and 256GB RAM support are excellent, but the buggy Aura Sync software drags the experience down.
44 PCIe lanes allow for a massive x16/x16/x8 multi-GPU setup perfect for rendering.
The BIOS is functional, but Fan Xpert 4 and Aura Sync are notoriously unreliable and poorly documented.
Best For
- Deep learning or 3D rendering rigs utilizing three GPUs in an x16/x16/x8 PCIe lane split.
- High-core-count Intel Cascade Lake-X workstations needing 256GB of quad-channel memory.
- Users who prefer manual BIOS tuning over relying on bundled Windows motherboard software.
Not Recommended For
- RGB enthusiasts who want seamless synchronization across different brands using Asus Aura Sync.
- First-time builders who might panic at a Q-code 00 or E1 POST error during initial setup.
Watch Out For
- The second M.2 slot (M.2_2) shares bandwidth and often won't show up in the BIOS until you manually configure the PCIe lane allocation.
- Fan Xpert 4 won't read your graphics card temperatures, meaning you can't tie your case fan curves to your GPU heat output.
- Setting the BIOS RGB lighting to 'Stealth' mode fails to turn off the I/O shield logo when the PC is powered off.
- The bundled 3D printing mount for the M.2 fan is poorly documented and requires hunting down outdated files on the Asus website.
Full Specifications
| RAM | DDR4 |
| ASIN | B07YD6SXF7 |
| Brand | ASUS |
| Series | Prime X299-A II |
| Voltage | 12 Volts |
| Platform | Windows 10 |
| CPU Model | Core i9 |
| Processor | 4266 MHz core_i9 |
| CPU Socket | LGA 2066 |
| Model Name | Prime X299-A II |
| Item Weight | 4.52 pounds |
| Chipset Type | Intel X299 |
| Manufacturer | ASUS |
| Memory Speed | 2133 MHz |
| Wireless Type | 802.11a/b/g/n/ac, 802.11ax |
| Item model number | Prime X299-A II |
| Compatible Devices | Personal Computer |
| Memory Clock Speed | 2133 MHz |
| Product Dimensions | 12 x 9.6 x 2 inches |
| Computer Memory Type | DDR4 SDRAM |
| Compatible Processors | Intel Core X-Series |
| National Stock Number | 0 |
| RAM Memory Technology | DDR4 |
| Item Dimensions LxWxH | 12 x 9.6 x 2 inches |
| Number of USB 2.0 Ports | 2 |
What Buyers Say
The hardware engineering on this board completely outclasses the software team's efforts. The 12-stage VRM and massive PCIe lane allocation make it a powerhouse for multi-GPU rendering rigs and heavy overclocks. Asus Aura Sync fails to recognize certified RAM, and Fan Xpert 4 lacks basic GPU temperature hooks. You will likely spend your first weekend fighting the BIOS to get your second M.2 drive recognized. Once configured manually, the board runs 24/7 without a single crash.
“Hardware is rock solid and handles my 10900X perfectly but the Asus software is absolute garbage and the I/O light refuses to turn off when I shut down the PC.”
Common Praise
- VRM heatsinks keep power delivery temperatures low even during 24-hour Prime95 stress tests.
- Easily hits 4266 MHz memory speeds with all eight quad-channel RAM slots populated.
- Included M.2 aluminum heatsinks drop NVMe drive temperatures by a proven 15-20°C.
- Diagnostic Q-Code LED on the top right corner saves hours of troubleshooting during initial POST.
Common Complaints
- Aura Sync software crashes frequently and fails to detect Corsair RGB memory.
- The Prime logo on the I/O shield stays glowing bright white when the PC is turned off.
- Fan Xpert 4 cannot read GPU temperatures to adjust case fan curves.
- Peeling the protective plastic off the VRM heatsink leaves torn plastic shards wedged in the metal grooves.
Ownership Tips
- The BIOS 'Stealth' mode for RGB lighting is bugged and will not turn off the I/O shield LEDs in the S5 power state.
- You must manually configure PCIe lane bifurcation in the BIOS to get the second and third M.2 slots to appear.
- Uninstalling Asus Armoury Crate and using third-party software for RGB and fan control drastically improves system stability.
- The thermal pads under the M.2 heatsinks are extremely sticky and can rip the label off your SSD if you ever need to remove it.
Frequently Asked Questions
Does this board support 10th Gen Intel Core i9-10900X out of the box?
Yes, the LGA 2066 socket and X299 chipset support Cascade Lake-X processors. You might need a quick BIOS update via USB flashback for absolute stability.
Why isn't my second M.2 NVMe drive showing up in the BIOS?
The M.2_2 slot shares PCIe lanes with other components. You have to go into the BIOS onboard devices configuration and manually assign the bandwidth to the M.2 slot.
Can I turn off the motherboard RGB lights when the computer is asleep or off?
You can try setting the BIOS ERP ready to S4+S5 and lighting to Stealth, but a known BIOS bug leaves the I/O shield Prime logo lit up anyway.
Does Fan Xpert 4 let me control case fans based on GPU temperature?
No. Despite Asus marketing images showing a GPU temp sensor icon, the software cannot pull thermal data from your graphics card.
What does Q-Code E1 or 00 mean on the diagnostic LED?
These codes usually indicate a memory training failure or a dead CPU. Reseat your RAM one stick at a time and check for bent socket pins.
Buying Guide
When buying an X299 HEDT motherboard, you are paying for PCIe lanes and memory bandwidth. This board gives you 44 lanes to run multiple graphics cards at full speed and supports 256GB of quad-channel RAM. Do not buy this for a standard gaming PC — it is built for 3D rendering, deep learning, and heavy video editing. Be prepared to bypass the included Asus Windows software and do all your fan and memory tuning directly in the BIOS.
LGA 2066 Socket & X299 Chipset
This is a massive physical socket designed exclusively for Intel's Core X-Series workstation processors, meaning standard desktop CPUs like an i9-13900K will not fit.
12 IR3555 Power Stages
Think of these as the engine's fuel injectors. 12 high-quality stages ensure a massive 165W+ processor gets clean, stable voltage without overheating the motherboard.
44 PCIe Lanes
Standard motherboards have 16 lanes for one graphics card. 44 lanes act like a multi-lane highway, letting you plug in three graphics cards and multiple NVMe drives without them slowing each other down.
Alternatives
If you just want a high-end gaming PC, look for a Z790 or X670E motherboard. If you need workstation features but want better software and dual 10G LAN, search for the Asus Pro WS or ASRock Creator series.
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