HP Z8 G4 and HP Z840 better value?

[SmileM]

Hello,

What is better value a 

1. HP Z8 G4

2. HP Z840

The systems both use outdated PCIE Gen 3, the biggest drawback of HP Z8 G4.

The only reason to upgrade to  HP Z8 G4 from HP Z840 is better cheap more power efficient CPU support in the future. 

The HP Z840 can be equipped with 1TB of RAM, best 2669V4 CPU for 1400Eur.

The HP Z8 G4 1TB RAM will cost 2400Eur, can I use slower 2400 Ram in it?

[SDH]

I'm going to defer to DGroves' opinion on this because he has worked much more with the 8 series of HP workstations over the years than me. But I do have some input:

You have some wrong ideas. You're right on the PCIe3 issue... both top out at that level of PCIe technology but you'd need to sell your first-born son to upgrade to PCIe4 in a Z8 G5. However, PCIe3 is a very fast and mature technology. PCIe4 hardware is backwards compatible with PCIe3. In fact, my testing with both the ZX G4 and ZX40 workstations shows that use of quality PCIe4 M.2 SSDs in either of those families gives faster performance than if you used a same-quality PCIe3 M.2 SSD.

There are more many more reasons to upgrade to a Z8 G4 from a Z840 than the single one you list, but at a significant upgrade in cost too. I personally think the Z840 will get you the best bang for your bucks, however, which is what you seem to want to know. Surely don't count on HP to certify any new processors for the Z840, and also likely not for the Z8 G4. They have to move on inexorably to the next and next... and it is quite expensive to do thorough conformance testing for older enterprise grade workstations.

The processors certified for the ZX G4 workstations clearly can be faster than those for the ZX40 workstations, but at a high cost currently. That will come down a lot, as it has already for the ZX40. My much lower cost tuned Z440 workstations can beat the one Z4 G4 I have (which is tuned to the degree I can justify spending on it currently). Down the road that Z4 G4 can be upgraded more. 

Regarding using slower cheaper RAM... big mistake. Slow RAM forces the other faster RAM sticks you might have in your workstation down to its own slow level. And it slows the processor(s) down to that same slow level too. Sometimes faster RAM actually is cheaper than older slower RAM, and sometimes newer used RAM recycled from retired servers is much cheaper than older slower workstation RAM. Servers retire before workstations so their recycled RAM supply is higher... you just need to know what you're doing and how to search for the best buys within eBay.

p.s. A tip:

With bifurcation turned on in a ZX40 PCIe3 x8 electrical slot you can insert a Z Turbo Drive Dual Pro card loaded with a PCIe4 M.2 stick in its primary socket as your boot/apps drive and a large cheaper PCIe3 M.2 stick in its secondary slot as your very fast documents drive. Having those two SSDs closely running side by side yields very fast performance. HP has been selling off their G1 version of those cards, new, through resellers on eBay for very low cost, and they work just as fast for me as the G2 Dual Pro card that was engineered with even better cooling for the ZX G5. I've posted details on these cards and their BIOS settings here in the forum. I've never had thermal throttling with our G1s, and I've tried.

[SmileM]

The Z8 G4 barebone no CPU, no RAM cost is 899Eur and Z840 can be found for 500/600Eur with CPU, and RAM that I do not need. 

Seems like ridiculous price for Z8 G4 given fact it has same PCI-E Gen3. 

Can anyone cralify PSU in Z8 G4. I thought that this is standard PSU 851385-001. With 230V it can give 1700W.

[SDH]

See below the attached HP QuickSpecs for the Z8 G4, v70, released 1 month ago. Page 8 shows the power supply variants... more than one.

[SmileM]

I noticed that dimensions of PC case is not changed:

Need I remind you PSU in HP Z8 G4 is on the side. So HP stole free space from inside the case?

Can anyone measure this ?

Dimensions

HP Z840   20.3 x 52.5 x 44.4 cm

HP Z8 G4   21.59 x 55.12 x 44.45 cm

Fitting RTX3090 etc it is very important that these should be same dimensions of free space as Z820 Z840 etc.

[DGroves]

neither system is qualified/approved for dual 3090 video cards, as the card draws up to 350 watts as such the 700 watt draw exceeds the z840's power supply max ratings

 it will overload the z840's multirail power supply's GPU subsection

even if the upgraded power supply is installed

also both systems will require dual cpu's to be installed to run dual dbl wide video cards in the available x16 slots

the z8 G4 may have thermal issues assuming dual cards will even fit

and it's  (1450 watt) upgrade supply is also not capable of running dual 3090 cards if dual high power cpu's are installed with ram /HD's/SSD's, and other pci-e cards installed

Power Supply Choice of:
1125W/100V/15A 90% Efficient wide-ranging, active Power Factor Correction
The power delivery system includes four 6+2-pin graphics power cables.

1450W/100V/15A 90% Efficient wide-ranging, active Power Factor Correction
The power delivery system includes four 6+2-pin graphics power cables.
1700W/200V/10A 90% Efficient wide-ranging, active Power Factor Correction
The power delivery system includes four 6+2-pin graphics power cables.

Notes: The 1125W/100V/15A (1450W at 200V Input Voltage) power supply can also supply 1275W of
output power when the input voltage is greater than 105V. If the input voltage is less than 105V, but
greater than 90V for any reason, the maximum power that can be drawn is 1125W. An uninterruptible
power supply (UPS) is highly recommended if 1275W output power is desired.

The 1125W Power Supply can also supply 1450W of output power when the input voltage is greater
than 200V under all conditions.

                                   
The 1450W/100V/15A (1700W at 200V Input Voltage) power supply can also supply 1550W of output
power when the input voltage is greater than 105V. If the input voltage is less than 105V, but greater
than 90V for any reason, the maximum power that can be drawn is 1450W. An uninterruptible power
supply (UPS) is highly recommended if 1550W output power is desired.

The 1450W Power Supply can also supply 1700W of output power when the input voltage is greater
than 200V under all conditions.

https://h20195.www2.hp.com/v2/getpdf.aspx/c05527763.pdf?ver=6#:~:text=Power%20Supply%20Choice%20of%3....

[SmileM]

I can see that 2x CPU can use 400W + 50W for RAM, then that would be 450W out of 1700W. I can count 1250W left, like you say 800W for 2x 3090, makes a 450W still left unused. Worst think I can add dedicated PSU in place of 2x 5.25inch bays.

[SmileM]

HP Z8 G4 adds support for AVX-512 extensions not found on E5-2699V4 for Z840, so that is the only upside in my book.