1Pcs 20/24 Pin LCD Computer PC Power Supply Tester for ATX BTX ITX TFX SATA with Buzzer Automatic Alarm
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AI Verdict
This cheap aluminum LCD tester is a must-have for your IT toolkit to instantly verify if a power supply is dead, but it won't diagnose under-load failures.
It serves as an excellent, inexpensive sanity check to see if a PSU is completely dead or missing a voltage rail. Because it only tests at idle, it cannot replace a proper multimeter or load tester for diagnosing complex stability issues.
If you need to diagnose random crashes under load, buy a digital multimeter to probe voltages while the PC is running.
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Pros
- LCD screen displays exact voltage readouts for +3.3V, +5V, +12V1, +12V2, -12V, and +5VSB to within +/- 0.01V
- Loud built-in buzzer automatically alarms if any voltage rail drops out of the ATX specification
- Includes dedicated ports for 20/24-pin ATX, SATA, Molex, Floppy, 4/8-pin CPU, and 6-pin PCIe
- Aluminum alloy casing survives getting tossed into the bottom of a heavy toolbag
Cons
- Only tests the power supply at idle — it cannot simulate a load to catch voltage droop during gaming
- The 8-pin port is strictly for CPU (EPS) power; an 8-pin PCIe cable will not fit
- Triggers false alarms on modern high-end PSUs if the Power Good (PG) signal is faster than 100ms
Dimension Scores
Measures output accurately at idle, but lacks load testing capabilities.
The buzzer is obnoxiously loud and piercing, making false positive alarms incredibly annoying.
The aluminum alloy shell is surprisingly durable for a cheap generic tool.
No cables of its own to manage, just plug the PSU cables directly into the block.
Best For
- IT professionals needing a quick diagnostic tool for dead PCs
- PC builders verifying a used or open-box power supply before plugging it into a motherboard
- Testing older ATX, BTX, ITX, and TFX power supplies
Not Recommended For
- Diagnosing random PC shut-downs that only happen during heavy GPU/CPU loads
- Testing proprietary power supplies from pre-built Dells or HPs with non-standard pinouts
Watch Out For
- The 8-pin port is for CPU power only. If you want to test an 8-pin (6+2) PCIe cable, you must plug the 6-pin part into the tester and leave the 2-pin dangling.
- False PG alarms are common. If your Power Good (PG) value flashes at 90ms or 120ms, your modern PSU is likely fine — the tester just has outdated timing thresholds.
- If the +3.3V light doesn't turn on when testing a SATA cable, don't panic. Many modern SATA cables are 4-wire and don't supply 3.3V anyway.
- It doesn't apply a load. A failing power supply with blown capacitors can still show perfect voltages on this tester but crash your PC the second you launch a game.
Full Specifications
| UPC | 661083376484 |
| ASIN | B07J9LRC6T |
| Brand | Comidox |
| Color | Black |
| Style | Compact |
| Item Weight | 3.2 ounces |
| Manufacturer | Comidox |
| Power Source | Corded Electric |
| Measurement Type | Voltmeter |
| Package Dimensions | 8.46 x 3.98 x 0.75 inches |
| Is Discontinued By Manufacturer | No |
What Buyers Say
This generic aluminum tester is a staple in IT toolkits because it instantly tells you if a PSU is dead. Buyers love the bright LCD that shows exact voltages rather than just 'good/bad' LED lights. The biggest headache is the outdated Power Good (PG) alarm, which constantly beeps at perfectly healthy modern power supplies. It is crucial to remember this is a no-load tester, meaning it won't catch a PSU that only fails when your graphics card spins up.
“Loud as hell and gave me a heart attack when it beeped at my brand new Corsair RMx, but it turns out the tester just doesn't like fast PG timings.”
Common Praise
- LCD screen gives exact voltage numbers instead of vague indicator lights
- Aluminum casing feels premium and survives drops
- Instantly identifies dead rails on older power supplies
- Draws power from the 24-pin cable so it never needs batteries
Common Complaints
- Piercing buzzer goes off constantly due to false PG value alarms
- 8-pin port doesn't accept PCIe cables, confusing many first-time users
- Doesn't test the power supply under actual load
- Instructions are poorly translated and don't explain the SATA 3.3V missing light
Ownership Tips
- The buzzer is so loud that some users put tape over the speaker hole to muffle it
- You will quickly learn to ignore the PG flashing if the value is under 150ms
- The 24-pin connector can be incredibly stiff to plug in and remove
Frequently Asked Questions
Why is my tester beeping and flashing a PG value of 120ms?
The tester expects a Power Good (PG) signal between 100ms and 500ms. Many modern, high-quality PSUs have fast PG timings that trigger a false alarm on this device.
Can I test my 8-pin GPU power cable with this?
Yes, but not in the 8-pin slot. The 8-pin slot is keyed for CPU (EPS) cables. You have to split your 6+2 PCIe cable and plug just the 6-pin connector into the tester.
Will this tell me if my power supply is causing my games to crash?
Probably not. This device tests the power supply with zero load. A failing PSU will often show perfect voltages here but fail when your GPU draws 300 watts.
Why isn't the 3.3V light turning on when I plug in my SATA power cable?
Many modern SATA power cables only use 4 wires and drop the 3.3V line entirely. The tester is accurately reporting that 3.3V is missing, but your drives don't need it anyway.
Does it need batteries?
No, the tester draws its power directly from the 20/24-pin ATX connector of the power supply you are testing.
Buying Guide
You are buying a basic continuity and idle voltage checker, not a professional load tester. It will tell you if a power supply is completely dead, if a specific cable is broken, or if a voltage rail is missing. It will NOT tell you if your power supply can actually deliver its rated wattage. Keep this in your drawer for quick sanity checks before building a PC, but don't rely on it to diagnose complex gaming crashes.
PG (Power Good) Value
This is the delay in milliseconds before the power supply tells the motherboard it is ready. The tester expects 100-500ms, but modern PSUs are often faster, causing annoying false alarms.
No-Load Testing
Like revving a car engine in neutral, this tests the power supply without making it do any actual work. It won't reveal problems that only happen when driving on the highway.
+/- 0.01V Accuracy
The LCD shows exactly what voltage is coming through the wires, letting you see if a 12V rail is sagging down to 11.4V even at idle.
Alternatives
If you need to diagnose random shut-downs under heavy use, skip this and buy a digital multimeter to back-probe your cables while the PC is running a stress test.
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