Hardware

Lenovo HR630x / HR650x Notes: LGA3647, 8259CL, Optane, and Common Pitfalls

Based on HR630x build logs and HR650x troubleshooting notes, this post summarizes buying and setup considerations for Lenovo HR630x / HR650x LGA3647 server barebones: CPU and Optane pairing, VRM unlocks, fan control, risers, backplanes, and BMC/UEFI notes.

Second-hand LGA3647 servers have become increasingly affordable, and Lenovo HR630x / HR650x machines retired from cloud deployments are now entering the homelab bargain-hunting scene. Their appeal is obvious: dual-socket Xeon Scalable, many memory slots, OCP networking, U.2 backplanes, IPMI management, plus the price advantage of some second-generation Xeon OEM CPUs and Optane PMem. It is easy to imagine a “thousand-yuan-class compute box” from these parts.

But these machines are not like upgrading a normal desktop PC. Before buying one, it is worth thinking through several pitfalls: motherboard versions, CPU generation, VRM power limits, memory compatibility, proprietary power supplies, fan noise, rare risers, hard-drive backplanes and trays, BMC passwords, and whether the BIOS is new enough.

This post reorganizes notes from two build reports. The goal is not to reproduce one exact build, but to make the trade-offs and traps around the HR630x / HR650x route clearer.

Platform Positioning

HR630x and HR650x are Lenovo hyperscale LGA3647 server platforms. In simple terms:

  • HR630x is a 1U machine, thinner and more constrained for expansion.
  • HR650x is a 2U machine, with more room for expansion, cooling, and installation.
  • The two platforms share many board-level references, so a lot of practical experience applies to both.
  • These machines are often cloud-retired units: cheap, but not always complete.

If you want a quiet, power-efficient server to sit next to your desk, these are not the best choice. If your goal is low-cost access to dual Xeons, more PCIe, many memory slots, and remote management, they are attractive.

Check Barebones Completeness First

When buying this kind of barebones system, do not look only at the base price. The real cost depends on what is missing.

Check these items carefully:

  • Whether both CPU heatsinks are included.
  • Whether all fans are present.
  • Whether the power supply count and wattage are enough.
  • Whether a U.2 / 2.5-inch drive backplane is included.
  • Whether the drive cables are included.
  • Whether drive trays are included.
  • Whether PCIe risers are included.
  • Whether the OCP NIC is included.
  • Whether the motherboard is the 24-DIMM or 16-DIMM version.

Some machines look cheap, but if they lack risers, trays, backplanes, or proprietary power supplies, later parts hunting can become more painful than the original purchase. This is especially true for HR650x risers, U.2 backplanes, and drive trays: they are not always easy to find on the used market, and the prices are not always friendly.

CPU: Why the Cheap 8259CL Needs Extra Work

One common value-oriented route is using a second-generation Xeon Scalable OEM CPU such as the Platinum 8259CL. It is cheap, has many cores and threads, and as a second-generation platform CPU, it can work with first-generation Optane persistent memory.

But cheap parts usually come with a reason. The 8259CL is an OEM model with a TDP of about 210W, slightly above the 205W limit many platforms expect by default. That difference looks small, but on some motherboards it can prevent the system from booting unless you modify the VRM controller’s current or power-related limit.

The common method is to use a USB-I2C tool such as MCP2221A, connect it to the motherboard’s VRM I2C interface, and write a new limit into VRM controllers such as PXE1610C. In the reference cases, the command form for HR630x / HR650x looks like this:

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ModTool.exe -PXE1610C 74 76

The point is not to copy the command blindly. First confirm your motherboard’s VRM model, I2C header location, SCL, SDA, GND pin order, and addresses. Wiring it wrong or using the wrong platform command is riskier than the CPU itself.

Prepare a Known-Good Boot CPU

If the machine arrives with an old BIOS, or if the VRM modification has not been done yet, installing an 8259CL directly may produce no display at all. In that case, a cheap first-generation Xeon as a boot CPU can make troubleshooting much easier.

A boot CPU is useful for:

  • Entering BIOS and checking the version.
  • Updating BIOS and BMC.
  • Confirming that the motherboard, memory, power supply, and fans are healthy.
  • Excluding basic hardware faults before modifying the VRM.

If the seller has already updated the BIOS and the machine can boot directly, the boot CPU may not be needed. For beginners, though, it greatly reduces debugging difficulty.

Optane PMem Is the Highlight of This Platform

Second-generation Xeon Scalable supports first-generation Intel Optane DC Persistent Memory, also known as DCPMM / PMem. It installs into DIMM slots and can be configured in BIOS as memory mode or as persistent block storage.

This is one reason CPUs like the 8259CL are attractive: when large DDR4 RDIMM / LRDIMM modules become expensive, used Optane PMem can be a low-cost way to add capacity.

However, Optane is not a complete replacement for normal DRAM. Keep these points in mind:

  • It requires a second-generation Xeon with DCPMM support.
  • The BIOS must support and correctly identify Optane.
  • DRAM is usually still required as cache or as a companion memory tier.
  • Slot placement and channel pairing should follow the Lenovo manual.
  • Performance sits between DRAM and SSD, so do not expect normal DRAM behavior.
  • You can create namespaces and use them as block devices such as /dev/pmem0.

If the goal is low-cost high-capacity memory experimentation, Optane is interesting. If the goal is maximum memory bandwidth, a low-channel-count Optane setup may not be suitable.

Memory Slot Versions and Compatibility

HR630x / HR650x may come in 24-DIMM and 16-DIMM versions. Before ordering, ask the seller for clear motherboard photos instead of trusting the listing title.

For memory, it is safer to buy the same brand, frequency, capacity, and rank in one batch. The reference build notes mention unstable recognition when mixing modules, and in some cases even swapping CPU or memory positions affected which memory was detected.

Safer rules:

  • Follow the official manual’s slot population order.
  • Avoid mixing too many brands and specifications.
  • When unsure, boot with the minimum configuration first.
  • On dual-socket platforms, verify the memory channels attached to each CPU.
  • When using Optane, double-check the DRAM and PMem channel pairing.

Server memory is not “if it fits, it boots.” The larger and more mixed the capacity, the higher the debugging cost.

Also, memory cannot be inserted randomly. Lenovo’s official documentation defines the DIMM population order for independent mode. Before building, check the slots against the manual, then expand from the minimum bootable configuration. This matters even more with dual sockets, mixed capacity, mixed rank, or Optane PMem; an incorrect layout may cause no boot, missing memory, or only the channels under one CPU being detected.

Do Not Underestimate Fans and Noise

These machines were not designed for bedrooms or home offices. The 1U HR630x is especially obvious: fan speeds are high, the sound is sharp, and the default boot policy can be very conservative.

According to the build notes, the default fan speed is high, and IPMI / CLI control is needed to reduce noise. After tuning, idle noise can be much better, but under full load with two high-power CPUs, the system still needs enough airflow.

When tuning fans, monitor:

  • CPU temperature.
  • VRM temperature.
  • PCH temperature.
  • Memory temperature.
  • PSU temperature.
  • Inlet and outlet temperatures.

Do not only watch the CPU. Many chips on server boards depend on chassis airflow. If fan speed is lowered too much, the CPU may still look fine while the PCH, VRM, or NIC overheats.

Changing Fan Speed

The fans on HR650x / HR630x can be controlled through IPMI raw commands. The community script uses this command format:

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ipmitool -I lanplus -H <BMC_IP> -U <USER> -P '<PASSWORD>' raw 0x2e 0x30 00 00 <SPEED>

<SPEED> can be treated as the target fan percentage. For example:

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# Set to 10%
ipmitool -I lanplus -H 192.168.1.100 -U ADMIN -P 'password' raw 0x2e 0x30 00 00 10

# Set to 35%
ipmitool -I lanplus -H 192.168.1.100 -U ADMIN -P 'password' raw 0x2e 0x30 00 00 35

# Set to 100%, useful for full-speed testing or thermal fallback
ipmitool -I lanplus -H 192.168.1.100 -U ADMIN -P 'password' raw 0x2e 0x30 00 00 100

If you run the command from the server OS itself and the IPMI kernel modules are loaded, you can avoid the BMC network path:

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ipmitool raw 0x2e 0x30 00 00 20

Before changing fan speed, confirm that ipmitool can read sensors:

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ipmitool -I lanplus -H <BMC_IP> -U <USER> -P '<PASSWORD>' sensor
ipmitool -I lanplus -H <BMC_IP> -U <USER> -P '<PASSWORD>' sdr

If local ipmitool reports no usable interface, load these modules on Linux:

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modprobe ipmi_devintf
modprobe ipmi_msghandler
modprobe ipmi_si

A safer approach is not to lock the fan at one very low speed, but to use temperature-based steps. For example:

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CPU below 40°C: 10%
CPU 40°C to 45°C: 14%
CPU 45°C to 50°C: 20%
CPU 50°C to 60°C: 50%
CPU 60°C to 80°C: 80%
CPU above 80°C: 100%

This can be implemented with shell, Python, or a systemd timer: read CPU temperature every few seconds, then write the corresponding fan percentage. The community HR650X-IPMI-Auto-Fan script follows this idea.

For manual tuning, start conservatively. Try 20% at idle first, verify that CPU, PCH, VRM, memory, NIC, and PSU temperatures are stable, then gradually try 14% or 10%. For full-load testing, do not begin with low fan speeds; start at 50% or higher, confirm cooling headroom, then find a balance between noise and temperature.

IPMI raw commands are vendor OEM commands, and behavior may differ across BMC firmware versions. Before running them, make sure the machine can read sensors normally and keep a terminal ready to switch the fans back to high speed. If temperature readings are abnormal, sensors show na, or fan speed does not change as expected, do not continue lowering the speed.

Power Supplies, Risers, Backplanes, and Drive Trays

One big HR650x pitfall is that the power supply interface and many expansion parts are not standard PC parts. The PSU uses a Lenovo-specific form factor, so replacing or adding one can be expensive.

Check risers in advance as well. Different risers support different card layouts, such as full-height full-length, full-height half-length, and half-height half-length. If you plan to install GPUs, HBAs, 25G/40G NICs, or NVMe adapters later, confirm the riser type before buying the machine.

Drive backplanes also have multiple configurations. You may see 2U.2, 4U.2, 8U.2, or 2.5-inch bay backplanes. Backplanes, cables, trays, RAID cards, or HBAs can all become extra costs.

A practical suggestion: if you only want the machine to boot and run compute jobs, do not rush to complete every tray and backplane. If your goal is all-flash storage or high expansion, include those parts in the total budget from the beginning.

BMC, BIOS, and Management

Cloud-retired machines often come with unknown BMC passwords. If you can enter BIOS, you can usually create or reset a management user there. If you can boot into an OS, ipmitool can also manage BMC users.

It is usually best to update BIOS and BMC to a newer stable version, for three reasons:

  • Support for more second-generation Xeon models.
  • Better Optane PMem detection and management.
  • Fixes for BMC, fan policy, or hardware compatibility issues.

The references mention that HR630x / HR650x may require BIOS updates for 8259CL and Optane. Different machine batches vary: some sellers have already updated them, while others require manual work.

The BIOS and BMC downloads for HR650x can be found through Lenovo’s support page:

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https://datacentersupport.lenovo.com/cn/zc/products/servers/thinksystem-hyperscale/hr650x/7x57/7x57cto1ww/j300cvx2/downloads/driver-list/

Also, HR650x supports Above 4G Decoding, but Resizable BAR support is not ideal. If you plan to install large-VRAM GPUs or use the machine for GPU compute, confirm BIOS options and power-cable plans first.

Who Should Try This

This kind of machine is better suited for people who:

  • Need many cheap x86 threads.
  • Can tolerate idle power draw and noise.
  • Have space for rackmount servers.
  • Are willing to read manuals, inspect board labels, and use a multimeter.
  • Can accept uncertainty in used-server parts.
  • Have patience for IPMI, BIOS, VRM, and DCPMM troubleshooting.

It is less suitable for people who:

  • Only want a quiet NAS.
  • Want a low-power 24/7 mini server.
  • Do not want to deal with BMC, fans, risers, backplanes, or proprietary PSUs.
  • Do not have spare CPUs, spare memory, or basic debugging tools.
  • Cannot accept BIOS updates, VRM modification, and fan tuning after purchase.

Summary

The main value of HR630x / HR650x is that they provide a low-cost LGA3647 dual-socket server platform. With cheap second-generation Xeons such as 8259CL and Optane PMem, they can become homelab compute nodes with impressive thread counts, memory capacity, and remote management.

The pitfalls are just as clear: high-power OEM CPUs may not be supported by default, so an MCP2221A VRM modification may be needed; memory slot versions and compatibility must be checked; fan noise and idle power cannot be treated like consumer hardware; risers, backplanes, drive trays, and power supplies can all add cost.

If the budget is tight and you enjoy tinkering, this is an interesting route. If you want something stable, quiet, and low-maintenance, calculate total power, noise, included parts, and future maintenance cost before jumping in.

References

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