Introduction to the HP Elite t655 Thin client - a cheap "lower power" AMD NUC from the suits at HP

Welcome to the short and succint guide to the HP Elite 655 thin client

(And yes, this is just a rewrite of the t640 guide...and no, I don't have a t655...yet)

So why should you care (as a home labber)?

It's a small-ish thin client, roughly 196mm W x 196mm H x 35 mm D , ~1.35 Liters, released Q3 2022, general availability in Q2 2023.

The HP t-series thin clients are like the quarter-waters of the AMD mini-NUC world. Not nearly as high end as the Chinese AMD NUC-clones like the Minisforums, its at least backed by a large US vendor.

In the t655, you have a Ryzen embedded R2314 APU within the AMD River Hawk family, which offers okay performance, low power usage/noise levels and a useable embedded GPU (Vega 6). It’s nearest consumer equivalent is the AMD Ryzen 3 3350U.

How much CPU and GPU firepower can I expect from one?

The Ryzen R2314 has a CPU configuration of 4 cores, 4 threads on a 12nm lithography process (it’s Zen+ and similar to the Picasso family of APUs). The performance/thermal envelope is comparable to the Intel i5-10210U or the i3-1115G4. System TDP is at 15w, passively cooled via convection.

The Radeon Vega 6 embedded GPU onboard has 6 Vega Compute Units arranged in a 384 Unified Shader: 24 Render Output Unit:8 Texture Mapper Unit configuration. Raw GPU horsepower is about 920 Gigaflops, roughly ~90% raw performance of a Steam Deck.

Base configuration as shipped is 8GB of RAM in 2 DDR4 DIMMs, and 32GB of eMMC in the M.2 slot using SD7 (SD storage via PCIe interconnect) - the first example being the Sandisk Mothim cards.

Base OS is HP ThinPro (a variant of Ubuntu Linux) or Windows 10 IoT edition x64.

What’s my path to expandability?

• 2 DDR4 Notebook RAM slots - officially supporting up 32 GB via a pair of 16GB DDR4 DIMMs, but 64GB (via a pair of 32GB SODIMMs) will also work.

ECC Support?

• Not supported, but not tested. But if it turns out like the t640 (which was tested) it'll function with ECC SODIMM inside, but the error correction will not be active.

• 2 M.2 slot -
- Key E (Wireless, HP/Allied Telesis AT27/29 M2 fiber NIC or PCIe x1)
- HP FlexIO for the option port (note that this is specific for the thin tx4x client line and not compatible with the EliteDesk line)
- Key B+M (NVMe only stated on the spec sheet)
- Sandisk Mothim SD7 cards (same as the HP t640)

• 2 USB3.1 ports in the back, 2 USB 2.0 ports (at an angle in the back), 2 USB 3.1 ports in the front, one USB 3.1 type C port in an option bay out back.
• USB 3.1 Gen 2 with power distribution is an option (L42726-000) on the breakout port, as is a serial port (L42732-000) and the micro display port (L42434-000). Note that USB-PD requires a 10 pin cable from HP that is not that easy to second source...but according to @Dave Corder you should be able to make a 10 pin 1mm pitch JST-SH straight-through cable from a 20 dollar crimping kit on Amazon to replace it.

Upgrade Compatibility with the t630/640/740/755
  • RAM: Yes, uses DDR4
  • M.2 (NVMe): Works fine - SATA not tested yet
  • m.2 Key A+E slot - the old M.2 fiber cards should fit, and as for the Wifi....you'll need to figure out how to run the antennas if it's not included in your particular SKU
Is there a guide to working inside the chassis?

HP has a policy of providing teardown/e-cycling guide for their hardware, and this is the one for the Elite t655 (it's a PDF file). Note that the teardown guide is the factory assembly procedure but in reverse. As for service manual, here's the user guide which includes opening/service instructions.

OS Compatibility with the Elite t655

The following is assuumed to work:

Windows 10 IoT/Pro, Windows 11
Debian Linux 10 to 12

How much am I expected to pay for one?

As of Q1 2024, they are rather expensive (300 quoted from known eBay vendors like Laptops4Les). Come back in Q2-Q3 2024 when their prices are expected to drop.

  • Slightly more performant than the t640
  • Three DisplayPorts coupled with a decent Vega 6 GPU
  • About 3% smaller than a 2019 Mac Mini (1.34L versus 1.37 L)
  • Passively cooled/fanless
  • M.2 NVMe upgradeability (and SD7 as well - SATA is not proven yet)
  • M.2 Key A+E PCIe slot can be used for wireless/fiber networking
  • The AT29M2-SC001 fiber NIC from the t630/730 can be re-used
  • If USB-PD option enabled, it can be a one-cable device (USB-PD power input, USB-C to HDMI output, bluetooth keyboard/mouse if the thin client comes with Wifi+BT.

• No IPMI, and no VPro (AMD DASH seem to be limited to Windows OS only)
• Only 2 DDR4 Notebook DIMM slots (64GB is the max, so about the same as the Intel 8th Gen NUCs)
• If upgrading from a t620 Plus/t630, it needs a 45w HP power brick, HP 7.0x4.5mm blue-ring-tip Notebook power plug. Those with the USB-PD option port can run it off USB-C power injection though.
• The default NIC is a Realtek GigE model, and they are known until recently for some truly crapulent showstopping drivers (also, no native ESXi driver, so no driver support for VSphere 7+)
• No PCIe slot (so it preludes quite a number of uses)
• The fiber NIC option based on a Broadcom Tigon, which also does not have native ESXi drivers - also no driver support for VSphere 7.
• The Vega 3 is a GCN5/VCN1 design (Navi/RDNA is not available until after the Renoir APUs). If you plan to use it as an HTPC box, it'll decode H264/H265 (HEVC) up to 4k, and VP9 is only assisted decoding. H264/H265 encoding is...not great compared to Intel Quicksync. AV1 encoding/decoding are not supported.

So, what can I do with it?

- Use it as a thin client.
You can drive up to 3 LCDs in 4k resolution (well, 4, if the option port has a miniDP or VGA breakout), so at the very least you can use Synergy to connect to multiple desktops. HP ThinPro out of the box can support various protocols like VNC, RDP, VNC RGS, NoMachine NX, AWS or Cendio ThinLinc. USB remote access is supported so you can in theory setup a remote VM in KVM and remotely connect USB and audio to it via the SPICE protocol.

So yes. Use it to drive multiple screens - delight friends, intimidate enemies.

- Run a “more powerful” firewall (as long as it’s gigabit and only require 2 ports (one of which is fiber based port ), or if you like the idea of USB3 based NICs).

The default port is a Realtek 8111, and the optional AT29M2 is Broadcom, Gigabit and duplex fiber based. There are USB 3.1 Gen2 ports for nBaseT networking, but that’s rather expensive.

- Low-medium performance expandable hypervisor.

Yeah, it’s more powerful than the R1505 of the outgoing t640, and SVM/RVI/AMDV-i is enabled. As long as you are comfortable with only 1-2 GigE ports in total, you could in theory load up a few VMs (with 32 to 64GB of RAM) and do some useful stuff with it. That being said, one M.2 NVMe card and potential Gigabit iSCSI is not your avenue to mind-blowing performance. ESXi is generally not recommended due to lack of native driver support for the Realtek NIC.

- Use it as an HTPC or as a living room PC.

It's very slightly smaller than the 2019 Mac mini, but you get expandable RAM (2 DDR4 SODIMM slots), storage (a single m.2 slot) and Gigabit fiber/wireless+bluetooh connectivity. It can play h264/h265/VP9 and any older format just fine. Not sure if Plex will allow you to do transcoding via AMD VCE/VCN support, though.

- You can do some light gaming on it

Expect it to perform like an AMD Ryzen 3 3350U in gaming.
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