HP Z8 G4 Workstation
The HP Z8 G4 is the biggest workstation of its generation — two Xeon Scalable sockets, up to 56 cores, 24 DIMM slots, and multi-GPU support for film, VFX, and simulation pipelines.
HP Z8 G4 Workstation — Refurbished Dual-Xeon Towers
The Z8 G4 sits at the top of HP’s Z-series: two Xeon Scalable sockets, 24 memory slots, seven PCIe slots and a power supply that will feed four graphics cards. It was never a cheap machine when new, which is exactly why the used market is interesting — a fully loaded Z8 G4 now costs a fraction of a new dual-socket workstation and runs the same Cascade Lake silicon that fills plenty of production racks today. Every Z8 G4 we ship is built to order, run under load on our bench, and covered by a free 1-year warranty including parts, labor and shipping.
HP Z8 G4 Specifications
| Form factor | Tower, 5U rack equivalent — 17.5″ H × 8.5″ W × 21.7″ D, 49.4–70 lb |
|---|---|
| Processors | Two Intel Xeon Scalable sockets — Bronze, Silver, Gold and Platinum parts across the Skylake-SP and Cascade Lake generations |
| Memory | 24 DIMM slots, ECC registered only. Up to 1.5 TB with two processors using RDIMMs, or 3 TB with 3DS LR DIMMs. RDIMM, LRDIMM and 3DS LRDIMM cannot be mixed |
| PCIe slots | Seven: three x16 and one x4 available with one CPU; slots 3 and 6 (both x16) and the widened slot 1 unlock when the second processor is installed. Plus two internal Gen3 x8 slots for M.2 storage cards |
| Drive bays | Four internal 3.5″, two external 5.25″ (175 mm depth limit), one 9.5 mm slim optical bay |
| Storage interface | 10-channel SATA 6 Gb/s with factory RAID 0/1/5/10 |
| Networking | Two integrated Gigabit ports; optional dual 10GbE |
| Rear I/O | Six USB 3.1 Gen1, serial, PS/2 keyboard and mouse, audio in/out |
| Power supply | 1125 W or 1450 W, 90% efficient, with four 6+2-pin graphics cables. Output scales with input voltage — see the note below |
Source: HP Z8 G4 Workstation QuickSpecs (linked below).
The power supply detail nobody mentions
Z8 G4 supplies are voltage-sensitive, and it changes what the machine can actually deliver. The 1125 W unit provides 1275 W above 105 V input and a full 1450 W above 200 V. The 1450 W unit likewise rises to 1700 W on a 200 V feed — but on a 100/110 V supply it ships with a 20-amp cord and needs a 20 A outlet, which many offices do not have at the desk. If you are planning a multi-GPU Z8, check the circuit before the machine arrives; we will confirm the supply and cord that match your site.
What is usually in stock
Our Z8 G4 inventory leans towards Xeon Gold pairs — 6126, 6136 and similar — with Silver 4108/4114 machines filling the value end, and the occasional Platinum build. Memory is typically 128 GB or 256 GB, with 768 GB configurations appearing regularly for virtualisation and simulation buyers. Graphics are mostly NVIDIA Quadro M4000 and P2000 on general-purpose builds, with P4000, P5000 and P6000 on the rendering machines. Anything larger — 1.5 TB of RDIMMs, four GPUs, 10GbE networking — is a build-to-order job; send us the spec and we will quote it.
Choosing between the G4 towers
- Z4 G4 — one socket, 8 DIMM slots, ordinary mains power. The right answer for a single CAD or design seat.
- Z6 G4 — also dual-socket but with 12 DIMM slots and a smaller chassis. Most of the Z8’s capability at a lower price, if you do not need the memory ceiling.
- Z840 — the previous generation on Xeon E5-2600 v3/v4. Cheaper again, and still a capable render node.
The full range lives on our refurbished HP workstations hub. If you are expanding a Z8 you already own, we sell registered ECC DDR4, Xeon Scalable processors and workstation graphics cards individually.
HP Z8 G4 Documentation
HP Z8 G4 Workstation QuickSpecs.pdf
HP Z8 G4 Workstation Data Sheet.pdf
HP Z8 G4 Workstation User Guide.pdf
HP Z8 G4 Technical White Paper.pdf
HP Z8 G4 — Common Questions
How much RAM does the Z8 G4 support?
1.5 TB across 24 slots with two processors and registered ECC DIMMs, or 3 TB using 3DS load-reduced modules — a configuration that needs 128 GB DIMMs HP no longer sells, so treat 1.5 TB as the practical ceiling. Only ECC registered memory is supported, and RDIMM, LRDIMM and 3DS LRDIMM types must not be mixed in the same machine.
Do I need both processors installed?
No, but three of the seven PCIe slots and half the memory slots depend on the second CPU. A single-processor Z8 G4 is a perfectly sensible machine; just size it knowing that slots 3 and 6 stay dark and slot 1 runs at x4 instead of x8.
Can I rack-mount it?
The chassis occupies the equivalent of 5U on its side. It is a tower first, so plan cooling and cable access accordingly if you intend to rack it.
Is buying a used Z8 G4 sensible in 2026?
For core count and memory capacity per dollar, yes. Xeon Scalable parts remain widely supported, DDR4 registered memory is cheap on the second-hand market, and the chassis is built for continuous duty. Where it loses is single-thread speed and idle power — if your workload is one thread waiting on a clock, a newer single-socket machine will feel faster.
What testing and cover does it come with?
Every unit is built to the ordered configuration and load-tested before packing. It ships with a free 1-year warranty covering parts, labor and shipping, which can be extended to five years at checkout, and returns are accepted within 90 days of purchase (RMA and restocking terms).