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The ASRock Rack 2U1G-B650/EVAC is a 2U server configuration built to cool higher-power AM5 processors—not a universal CPU cooler you can drop into any rack case. Its larger air-cooling assembly is designed for CPUs in an approximately 170 W thermal class, with chassis and airflow changes that make room for it. That extra headroom comes with trade-offs, including less GPU thickness and drive-bay capacity than the standard 2U1G-B650.
What EVAC means
EVAC stands for Enhanced Volume Air Cool. It describes ASRock Rack’s higher-capacity air-cooling configuration for the 2U1G-B650 platform. The larger heatsink uses eight copper heatpipes and enlarged fin stacks, extending the cooling assembly toward the front of the chassis. It is not a different socket or motherboard platform; it is a cooling-and-chassis configuration for a specific 2U system.
That distinction matters when buying. ASRock Rack’s product listing is for the 2U1G-B650/EVAC server barebone. The available product information does not establish that the heatsink is broadly sold as a standalone retail cooler. Treat EVAC as an integrated system configuration, not a generic AM5 upgrade.
Why the chassis is part of the cooler
A 2U enclosure leaves much less vertical space for a heatsink than a tower case. Cooling a high-power processor therefore depends not only on heatsink size, but also on how air is directed through the server. ServeTheHome reports that the EVAC assembly needs additional chassis mounting points and that the fan partition must be relocated toward the front to make room. The airflow guide, GPU riser and cabling also need to be positioned with clearance in mind.
#1 Best Overall
- 2U Rackmount with 1+1, 80-PLUS Platinum, 1200W CRPS
- Single Socket AM5 (LGA 1718), supports AMD EPYC 4005/4004 and AMD Ryzen 9000/8000/7000 Series Processors
- 4 DIMM slots (2DPC), supports DDR5 ECC/non-ECC UDIMM
- 2 optional fixed 2.5" drive bays
- 1 FHFL triple-slot PCIe5.0 x16
Do not force the heatsink into a standard chassis or assume that another AM5 board will fit the arrangement. If the assembly does not line up, stop and confirm the chassis revision and follow the official assembly guidance. Improvised changes to a fan wall or baffle can undermine airflow even if the parts physically fit.
What the cooling results show—and what they do not
ASRock Rack’s comparison material places EVAC in an approximately 170 W CPU thermal class, compared with about 120 W for the standard 2U1G-B650. ServeTheHome tested the larger cooler in connection with EPYC 4004 systems, including the 16-core, 170 W EPYC 4564P, and reported temperatures roughly 9–13°C lower in hotter configurations than with the less substantial cooling setup.
That is a result from a particular test system, not an ASRock guarantee or a promise that every CPU will run that much cooler. Inlet temperature, CPU power limits, workload, fan profile, firmware, dust, GPU heat and rack airflow all affect temperature and sustained boost behavior. A nominal 170 W TDP does not guarantee unrestricted operation at that power in every environment.
Rank #2
- 1U Rackmount with 1, 80-PLUS Gold, 315W PSU
- Single Socket AM5 (LGA 1718), supports AMD Ryzen 7000 series processors
- 4 DIMM slots (2DPC), supports DDR5 ECC/non-ECC UDIMM
- 2 hot-swap 2.5" SATA drive bays
- 1 fixed 3.5" SATA drive bay or 1 Slim ODD
Supported CPUs and the rest of the platform
ASRock Rack lists the EVAC platform for AMD EPYC 4005 and 4004 processors and Ryzen 9000, 8000 and 7000 Series CPUs. Check the current CPU-support information and required BIOS version for the exact processor before ordering. A CPU appearing on a support list is not by itself proof that a particular workload, ambient temperature or GPU configuration will have adequate cooling.
The barebone is a single-socket AM5 (LGA1718) 2U rackmount system. Its platform features include:
- Four DDR5 UDIMM slots supporting ECC or non-ECC memory. This is not an RDIMM platform; buyers expecting the memory capacities common to larger EPYC servers should account for that limitation.
- One full-height, full-length, dual-slot PCIe 5.0 x16 expansion position and one full-height, half-length PCIe 4.0 x4 slot.
- Two M.2 slots and one optional fixed 2.5-inch drive bay. Platform coverage identifies one M.2 slot as PCIe Gen5 x4 from the CPU and the other as PCIe Gen4 x4 through the B650 chipset, sharing chipset I/O bandwidth.
- Two Intel i210 1GbE ports and remote IPMI management.
- Redundant 1+1 1200 W 80 PLUS Platinum CRPS power supplies.
These are system features, not properties of the heatsink. Confirm what is included in a particular barebone listing: processor, memory, storage and GPU should not be assumed to come with it.
Rank #3
- M/B size: Micro-ATX 9.6 x 9.6 / mini-itx 6.7 x 6.7
- Drivebay: Supports eight hotswap 2.5"/3.5" SAS/SATA HDD/SSD+1x Slim ODD+ 2x2.5"
- Cooling System: 4 x 80mm PWM Fan
- PSU: Supports standard ATX power supply with fan on side (80mm)
- Rail: Include 1set 20" sliding rail step 1）Install the inner rails onto the chassis. sep 2) Install the outer rails onto the rack. step 3) Slide the chassis (with inner rails attached) into the outer rails on the rack.
EVAC vs. standard 2U1G-B650 vs. AQUA
| Configuration | Cooling and CPU class | Expansion and storage trade-off | Best fit |
|---|---|---|---|
| 2U1G-B650 | Standard air cooling; comparison material lists up to about 120 W | Triple-slot main GPU position and two optional fixed 2.5-inch bays | Lower-power CPUs or builds where GPU thickness and drive capacity matter more than additional CPU thermal headroom |
| 2U1G-B650/EVAC | Larger air-cooling assembly; listed up to about 170 W | Dual-slot main GPU position and one optional fixed 2.5-inch bay | Higher-power CPUs and sustained workloads where air cooling and more CPU thermal margin are priorities |
| 2U1G-B650/AQUA | Liquid-cooled alternative in the family | Check the exact factory configuration and service arrangements | Deployments with a specific reason to choose liquid cooling and a plan for its maintenance |
The standard-versus-EVAC figures and slot/bay distinctions come from ASRock Rack’s GPU server comparison material. ServeTheHome describes standard air cooling, EVAC and AQUA as distinct cooling approaches within the family. Neither EVAC nor AQUA is universally superior: workload, inlet temperature, serviceability, noise targets and sourcing all matter.
Who should consider EVAC?
- Higher-power EPYC 4004 or Ryzen 9 builds: The larger heatsink is most relevant when the CPU will spend long periods under multicore load rather than brief bursts.
- GPU-assisted systems: More CPU cooling capacity can be useful in a compact enclosure, but the dual-slot limit makes exact GPU thickness, length, power connector position, riser arrangement and airflow essential checks.
- Warm or airflow-constrained installations: EVAC provides more cooling hardware, but it cannot compensate for hot intake air, blocked exhaust or GPU heat recirculating into the CPU’s airflow path.
- Air-cooling preference: It offers a factory-integrated air solution for this chassis where an improvised desktop cooler may not fit or direct air correctly.
Who may be better served by another configuration?
The standard 2U1G-B650 is a more natural fit if a lower-power CPU—such as the 65 W Ryzen 9 7900 cited in platform coverage—is sufficient and triple-slot GPU clearance or two optional 2.5-inch bays are more valuable. Consider the AQUA version only if the workload justifies liquid cooling and the deployment has a validated service plan.
Look elsewhere if you need registered DDR5 memory, several native drive bays, triple-slot GPU support in this chassis, or a universal standalone AM5 cooler. A conventional 2U server with a third-party heatsink can be an alternative, but only after validating cooler height and mounting, airflow direction, fan-wall pressure, riser clearance and cabling as a complete system.
Rank #4
- Micro-ATX (9.6"x 9.6")
- Support AMD Ryzen 7000 series Processors
- 4 DIMM slots (2DPC), supports DDR5 ECC/non-ECC UDIMM
- 1 PCIe5.0 x16, 1 PCIe5.0 x4, 1 PCIe4.0 x1
- Supports 1 M.2 (PCIe5.0 x4)
Installation, maintenance and troubleshooting
Before installation, verify that the chassis has the EVAC-specific mounting points and that the fan partition and airflow guide are in the intended positions. Check clearance at the GPU riser and SATA cabling; do not force a misaligned heatsink. The public hands-on coverage confirms the mechanical constraints but is not a substitute for the model’s official assembly instructions.
If CPU temperatures are higher than expected, check the thermal interface and heatsink mounting, fan direction and PWM control, baffle alignment, rack inlet temperature, fin-stack dust, GPU heat recirculation, CPU power limits and whether the system is using the EVAC airflow arrangement. Dense fins may call for more regular filter and fan maintenance in dusty environments; available coverage does not establish a quantified dust-related failure rate.
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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →If performance falls during sustained work, investigate thermal throttling, conservative fan curves, restricted rack airflow, GPU heat and firmware or power-management settings. Record CPU package temperature, effective clocks, package power, fan speed, inlet temperature and workload duration. A single peak-temperature reading cannot tell you whether the system sustains the performance you need.
Buying checks
- Confirm the listing is for the complete 2U1G-B650/EVAC barebone, not the standard model or an unspecified cooler.
- Verify CPU support and BIOS requirements for your exact chip.
- Confirm memory is compatible DDR5 UDIMM, not RDIMM.
- Check GPU dimensions and the dual-slot limit, plus the riser and power-cable layout.
- Verify drive-bay configuration, PSU inclusion, warranty, return policy and distributor stock.
Availability can be limited because this is a specialized server barebone. A Newegg listing observed during research was out of stock and displayed $1,720.99, but that is a date-specific marketplace snapshot, not a current price or a reliable indication of general availability. Check the seller’s current listing and terms before planning a build.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
