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HP EliteOne 840 23.8 inch G9 All-in-One Desktop PC

Ranked #29 of 41 in Most energy-efficient all-in-one PCs, ranked on official ENERGY STAR power figures. Here is every spec we scored, where it came from, and how it compares.

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H

#29

HP EliteOne 840 23.8 inch G9 All-in-One Desktop PC

Best for: Official TEC 63.5 kWh, official sleep 3.8 W

2.7/10

What we like

Official ENERGY STAR record lists a TEC of 63.5 kWh.

Watch out for

Official TEC is a certified laboratory annual-energy figure for this configuration, not a utility bill we measured.

Score breakdown

Official TEC 45%

Official sleep power 30%

Official short-idle power 25%

Official TEC	63.5 kWh
Official sleep power	3.8 W
Official short-idle power	16.8 W
Official ENERGY STAR unique ID	4,510,378
Official model name	HP EliteOne 840 23.8 inch G9 All-in-One Desktop PC (ENERGY STAR)
Official model number	HSC-Q002-24
Official product type	Integrated Desktop
Official TEC	63.5 kWh
Official sleep mode power	3.8 W
Official short-idle power	16.8 W
Official long-idle power	3.8 W
Official off-mode power	1 W
Official system memory	64 GB
Official CPU cores	24
Official processor brand	Intel
Official processor name	Core i9
Official CPU base clock	2 GHz
Official storage technology	SSD
Official ENERGY STAR date certified	2025-09-26T00:00:00.000
Official integrated display size	23.8 in
Official integrated display resolution	2.07 MP
Official touch screen	No
Official internal PSU rated power	240 W
Price	Check price

Check price at Amazon

Specs sources:

HP EliteOne 840 23.8 inch G9 All-in-One Desktop PC head-to-head

Head-to-headApple iMac (M4, four ports) vs HP EliteOne 840 23.8 inch G9 All-in-One Desktop PC

How it compares

Open the full comparison table

HP 21.45 inch All-in-One Desktop PC 22-dg

#1 · Official TEC 34.9 kWh, official sleep 1.4 W

Lenovo ThinkCentre neo 55a 24 Gen 6

#2 · Official TEC 38.8 kWh, official sleep 0.9 W

Lenovo IdeaCentre AIO 24AKP10

#3 · Official TEC 44.3 kWh, official sleep 1 W

Lenovo IdeaCentre AIO 27AKP10

#4 · Official TEC 44.3 kWh, official sleep 0.8 W

HP OmniStudio 23.8 inch All-in-One Desktop PC 24-cv

#5 · Official TEC 44.1 kWh, official sleep 1.9 W

Apple iMac (M6, two ports)

#6 · Official TEC 53.5 kWh, official sleep 0.4 W

Lenovo ThinkCentre neo 50a 24 Gen 5

#7 · Official TEC 51.5 kWh, official sleep 1.5 W

Lenovo IdeaCentre AIO 27ILL11

#8 · Official TEC 49.1 kWh, official sleep 2.1 W

Lenovo ThinkCentre neo 50a 27 Gen 6 LNL

#9 · Official TEC 49.1 kWh, official sleep 2.1 W

Apple iMac (M4, two ports)

#10 · Official TEC 57.7 kWh, official sleep 0.6 W

HP OmniStudio 23.8 inch All-in-One Desktop PC 24-cu

#11 · Official TEC 48.9 kWh, official sleep 2.2 W

Apple iMac (M6, four ports)

#12 · Official TEC 57.4 kWh, official sleep 0.8 W

Lenovo ThinkCentre neo 50a 24 Gen 7

#13 · Official TEC 49.3 kWh, official sleep 2.7 W

Lenovo ThinkCentre neo 50a 27 Gen 7

#14 · Official TEC 49.9 kWh, official sleep 2.7 W

Lenovo ThinkCentre neo 50a 27 Gen 5

#15 · Official TEC 56.3 kWh, official sleep 1.6 W

Dell 24 All-in-One EC24260

#16 · Official TEC 52.3 kWh, official sleep 2.6 W

HP ProOne 440 23.8 inch G9 All-in-One Desktop PC

#17 · Official TEC 55.6 kWh, official sleep 2.1 W

Lenovo Yoga AIO 27IPH11

#18 · Official TEC 56 kWh, official sleep 2.2 W

Apple iMac (M4, four ports)

#19 · Official TEC 63.6 kWh, official sleep 0.9 W

Lenovo IdeaCentre AIO 24ILL11

#20 · Official TEC 54 kWh, official sleep 3.1 W

Lenovo ThinkCentre neo 50a 24 Gen 6 LNL

#21 · Official TEC 54 kWh, official sleep 3.1 W

Lenovo IdeaCentre AIO 27IPH11

#22 · Official TEC 58.3 kWh, official sleep 2.4 W

HP OmniStudio 27 inch All-in-One Desktop PC 27-cu

#23 · Official TEC 59.6 kWh, official sleep 2.5 W

Lenovo ThinkCentre M90a Gen 5

#24 · Official TEC 62.1 kWh, official sleep 2.3 W

MSI PRO MAX 27TP Z 8MG

#25 · Official TEC 60.7 kWh, official sleep 2.5 W

Dell 27 All-in-One EC27260

#26 · Official TEC 60.1 kWh, official sleep 2.9 W

Lenovo ThinkCentre M70a Gen 6

#27 · Official TEC 63.3 kWh, official sleep 3.3 W

Lenovo ThinkCentre M90a Gen 6

#28 · Official TEC 77.5 kWh, official sleep 1.3 W

HP EliteStudio 8 All-in-One G1i 27 inch Desktop AI PC

#30 · Official TEC 72 kWh, official sleep 2.5 W

HP OmniStudio 27 inch All-in-One Desktop PC 27-cv

#31 · Official TEC 71 kWh, official sleep 3 W

Lenovo ThinkCentre M90a Pro Gen6

#32 · Official TEC 91.3 kWh, official sleep 1.3 W

HP ProStudio 4 All-in-One G1i 23.8 inch Desktop AI PC

#33 · Official TEC 67.6 kWh, official sleep 3.9 W

Lenovo ThinkCentre X AIO

#34 · Official TEC 81.4 kWh, official sleep 2.2 W

HP EliteOne 870 27 inch G9 All-in-One Desktop PC

#35 · Official TEC 77.2 kWh, official sleep 2.8 W

MSI Modern AM242TP 1M

#36 · Official TEC 68.7 kWh

MSI Modern AM272P 1M

#37 · Official TEC 68.7 kWh

HP OmniStudio X 31.5 inch All-in-One Desktop PC 32-c

#38 · Official TEC 81.1 kWh, official sleep 2.4 W

Lenovo Yoga AIO 32ILL10

#39 · Official TEC 90.3 kWh, official sleep 2.1 W

HP OmniStudio X 27 inch All-in-One Desktop PC 27-cs

#40 · Official TEC 81.6 kWh, official sleep 2.6 W

MSI Modern AM273Q AI 1UMG

#41 · Official TEC 92.4 kWh, official sleep 4 W