Reference Material Introduction to the HP t740 Thin client - the little box that could but better

Welcome to the short and succint guide to the HP t740 thin client
(Also known by HP internal codename Pichu)

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

It's a large-ish thin client, roughly in the dimensions of 210mm W x 210mm H x 50 mm D, ~2.20 Liters, released in Q3 2019, GA in Q2 2020.

The HP t-series thin clients are about as close as AMD got to releasing an intel NUC competitor, and on their big expandable clients (t620 Plus, t730, t740) you are offered an AMD NUC but with a PCIe 3.0 x16 slot (of which x8 are populated)
Laissez les bon temps rouler!

In the t740, you have a Ryzen embedded APU from the AMD Great Howled Owl family, which offers solid performance, low power usage/noise levels combined with one thing that Intel NUC owners wish they have, and until the NUC9 came along in late early 2020, something that they didn't have - a full size low form factor PCIe x16 slot, which opens up some good possibilities. Even at the currently inflated retail pricing (as of Q2 2020 - about 600 USD for a base model) the t740 is still significantly cheaper than the NUC9s (starts at 700 USD...?).

In the t740, you can expect hardware SRIOV/passthrough support in Linux (which is an exciting feature), but with one major caveat - PCIe ARI forwarding was disabled so you can only have up to 7 PCIe virtual functions in total. That might be sufficient for very useful microserver functionalities.

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

The Ryzen V1756B has a CPU configuration of 4 cores, 8 threads on a 14nm lithography process. The CPU performance is slightly above a Ryzen 5 2600H and outpaces the more expensive quadcore i3-8100B inside the Mac Mini 2019.

The Radeon Vega 8 embedded GPU onboard has 8 Vega Compute Units arranged in a 512 Unified Shader:32 Render Output Unit:16 Texture Mapper Unit configuration. Raw GPU horsepower is about 1333 Gigaflops, roughly the same as the XBox One (12 GCN2 CUs) or the nVidia GT1030.

Base configuration as shipped is 8GB of RAM in 2 DDR4 DIMMs, and 64GB of eMMC in the NVMe/eMMC M.2 slot. The SATA M.2 is usually empty but a retaining screw is included.

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 (currently supporting up 64 GB via a pair of 32GB DDR4 SODIMMs - official support is 32GB in 2x16GB modules)
• 3 M.2 slots -
- Key E (Wireless, or PCIe x1)
- Key M (NVMe/eMMC)
- Key B+M (SATA)

• 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 up front
• One PCIe 3.0 x16 small form factor slot, 75 Watt max (although that has not been 100% documented so I'll be wary about anything over, say, 50w)

Upgrade Compatibility with the t730
  • RAM: Nope - the t740 requires DDR4. The t730 is DDR3
  • PCIe Key M (NVMe/eMMC) - not present on the t730
  • PCIe Key B+M (SATA): Works fine
  • PCIe Key E slot - the old fiber cards will not 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
  • PCIe 3.0 x16 slot - should work for the most part.
What can I do with that PCIe 3.0 x16 slot (really an x8)?

The following bas been tested and known to work:

• Intel i340-T4 Quadport GigE cards
• SolarFlare SFN5122F 10GbE card
• SolarFlare SFN7122F 10GbE card
• Mellanox ConnectX3 VPI 40GbE/Infiniband adapter (MCX354A-FCBT)

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 t740 (it's a PDF file). Note that the teardown guide always reference the product codename and it looks like the factory assembly procedure but in reverse.

What does the power usage look like?
(All figures assume 2x32GB DDR4-2666 SODIMM, 512GB m.2 SATA SSD, and a Mellanox ConnectX3 VPI Dual 40/56GBit NIC/IB HBA)
Vampire Draw (powered off and connected to the wall): 2w.
Idling, Proxmox VE 6.2, no VMs running, 17-21w
Idling, Windows 10 Pro driving a 1080p screen via HDMI, 21-24w
Idling, Proxmox VE 6.2, 4 VMs running, 3 with 2 VFs assigned - 27-31w
Windows 10 Pro playing Super Mario Galaxy within Dolphin, 2x native resolution, 1x MSAA: 41-45w
WIndows 10 Pro playing 4k VP9 via Google Chrome + Youtube: 49-55w
Fully stressed, Proxmox 6.2, stress-ng -c 30 -vm-bytes 1G -m 60, and 3 VMs running, each with two SRIOV SFs: 87-90w

OS Compatibility with the t740

The following has been tested and known to work:

Proxmox 5.2/6.1
VMWare ESXi 6.0U3/6.5U3 (requires custom ISO for Realtek NIC)
Windows 10 IoT/Pro
Debian Linux 10

How much am I expected to pay for one?

As of Q2 2020, about 400-450 USD for a refurb unit, but they will get cheaper as time goes on.

  • Much more performant than the t730
  • Quad DisplayPort support coupled with a halfway competent Vega 8 GPU
  • About 10% smaller than the t730, and only 60% bigger than the 2019 Mac Mini
  • Nearly silent with a single general purpose fan, and only 15% louder than the t730 under load
  • Low profile PCIe x16 slot
  • Both NVMe and SATA are present
  • AMD-vi, HSA and limited SRIOV support baked into the BIOS
  • Professional looking and can be made rather inconspicuous with the HP under-desk thin client mounting kit

• No IPMI, and no VPro (AMD DASH seems to be limited to Windows clients only)
• Only 2 DDR4 Notebook DIMM slots (64GB is the max, so about the same as the Intel "Lake" series)
• Need a different 90w HP power brick, HP 4.5mm blue-ring-tip Notebook power plug
• The default NIC is a Realtek GigE model, and they are known until recently for some truly crapulent showstopping drivers (and no native driver support in ESXi)
• Nearly 15% louder than the t730 under load
• AMD Vi works, PCIe Access Control Services work, but ARI forwarding doesn't, so even though SRIOV works you are limited to 7 Virtual functions in total. Not sure if this is hardware imposed or an AGESA embedded firmware limitation. Later revisions of the BIOS (or a hacked BIOS) might* be able to unlock this. The SRIOV functionality doesn't seem to work in ESXi 6.0/6.5.
• The Vega 8 is GCN7/VCN1 design (this is before Navi/RDNA). If you plan to use it as an HTPC box, remember that it'll decode H264/H265 (HEVC) at up to 4k, and VP9 is only assisted decoding. H264/H265 encoding is...not that great.

So, what can I do with it?

- Use it as a thin client.
You can drive up to 4 LCDs in 4k resolution, 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 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 “much more powerful” firewall.
Many people here swears by the t620 Plus, but if you have some serious packet filtering, you could in theory toss in a dual port 1/10/40GbE card on the t740, toss up a virtual function or 2 via SRIOV to accelerate throughput, and work successfully with higher line speeds.

- Medium performance expandable hypervisor.
Yeah, it’s about the same horsepower as a Kaby Lake, and SVM/RVI/AMDV-i is enabled. SRIOV is supported in Linux but VMDirectPath (its VMWare equivalent) doesn't seem to work, unfortunately. You could in theory load up at least 8-12 VMs (with 64GB of RAM) and do some useful stuff with it. Oh yeah, since it has a PCIe x8 slot (PCIe x16 form factor), you can toss in a Mellanox 10/40 GbE card and use it to talk to an iSCSI or NFSv4 mount on a legit NAS/SAN setup.

- Use it as an HTPC or as a living room PC.
It's about ~60% bigger than a Mac Mini (1.4 L for a Unibody or USB-C MacMini, versus 2.2 L for the t740), but you get expandable RAM, storage (in 2 m.2 slots) and a PCIe x16 slot. Add a 10/40GbE card, run some singlemode fiber to a 10/40GbE NAS, and you can have the world's best equipped HTPC, and it can play h264/h265/VP9 and any older format just fine. You want something smaller? There's the t640, and it's 1.4 L. Only 1 M.2 SATA slot (unverified) though, and no PCIe x16 slot. But you can use the fiber NIC from the t730 on the t640.

- You can do some moderate gaming on it
It should behave like a Kaby Lake PC with a mainstream GPU from 2017, and if you need extra horsepower, toss in a GT1050 PCIe card (with active cooling, please) and you’ll be able to play modern titles okay.

Are there similar products out in the market today?

The DFI DT122-GH is its industrial PC equivalent but is not in general circulation yet.

Are there active discussion on STH for this device?

I have a running discussion involving its possible use as a computing node upgrade for a t730 thin client.
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Great overview of the T740
There's a running discussion on using the t740 as a Microserver. Right now, for a less-than-400 dollar machine (assuming you did not pay retail pricing), it's actually quite good (you can do SRIOV in Linux?! On a tiny little machine like this?)

I wonder if a smart admin would be able to use SRIOV to split a Mellanox or a Chelsio 10/40/100GbE card to various VFs and use 2 of them in an HA setup for line-speed pfsense duty on Proxmox or something.