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August 29th, 2025 12:40
Vostro 14 5402 – Severe CPU Throttling (Motherboard Fault) – Dell Support Ignoring Evidence
Description:
I’ve honestly had enough of this laptop and the way Dell is treating me. I bought a Vostro 14 5402 at the start of 2021 thinking it would be a reliable machine for school, but from the very beginning it has been nothing but a headache.
When I first got it, the laptop would crash randomly — my browser would turn completely black, and sometimes the whole machine would freeze. Then as a result, my brother had to reset it just to get it semi-usable. I thought that maybe this was just how these machines ran, and I sucked it up for the first 4 years, even though it always felt slower than it should. But in the past few months it has gotten unbearably bad, and I finally started digging into benchmarks and monitoring to find out the truth.
Performance Testing
Cinebench R23 scores: 667–1238 multicore (multiple tests ran for reliability of the results). An i7-1165G7 should be scoring 5000–6000+.
→ My machine is running at less than 20% of its intended performance, making it effectively useless.HWInfo64 shows the CPU is 100% power-limited by PL1 (8–12 W) when it should be running at ~28 W sustained and up to 51 W boost.
Temperatures are normal (60–70 °C). This is not thermal throttling.
BIOS detects chargers correctly (65W and 130W Dell chargers). So it’s not an adapter problem.
Battery Behavior
On battery, the problem is still there.
If I unplug and re-plug the charger, or unplug/re-plug the battery, the CPU boosts correctly (2–3 GHz, higher watts) — but only for a few seconds or minutes before the EC clamps it back down.
I tested with the battery completely disconnected and a 130W Dell XPS charger — issue was still there.
If this was purely a battery fault like the Dell agent claimed, then with the battery removed it should run fine. But it doesn’t.
👉 This proves it is not a battery issue. It is a board-level Embedded Controller / power delivery fault that has been present since day one.
Motherboard Fault Symptoms I’m Experiencing
Severe CPU throttling (locked to <0.6 GHz / <8 W in many cases).
Random fan ramping to high RPM even at low temps.
Black screen / browser crashes early on.
Battery degradation happening much faster than normal.
CPU only works properly for a few minutes after resetting the power state (unplug/re-plug).
Performance worse without the battery connected, proving the board relies on it to buffer power.
Other Hardware Defects / Build Quality Issues
The Screw near the Ethernet port ripped out of the motherboard after only a few months of use.
The rubber grips on the bottom case fell off after light use - within <4 months of use
Some of the plastic grills broke under little to no pressure, showing weak chassis design.
The speakers died completely despite no abuse or rough handling.
- Fingerprint reader stopped working multiple times within the first few months of purchase requiring to reinstall the driver multiple times during that time period. Then the fingerprint stopped working entirely after 1.5 years.
This laptop has had defects across the board, both in build quality and performance. It is not of acceptable quality under ACL.
Dell Support
The last agent I spoke to was completely unprofessional and claimed that he had been working for “5 years” so he was correct. He kept insisting I buy a new battery and upgrade my RAM, even though I explained that:
The issue remains even with the battery disconnected.
My sister’s older Vostro with a worse battery, and my brother’s XPS that lasts 5 minutes on battery, do not throttle like this.
The system was comfortably running on 16 GB RAM and 16 GB is still the recommended spec today.
Furthermore Dell, I have no problem buying a new genuine Dell OEM battery later, but only if Dell acknowledges that this is a board-level fault and covers the motherboard replacement at no cost to me.
Escalation & Consumer Rights
This case needs to be escalated to a Level 2 technician or case manager. I will not accept “buy a new battery first” as an answer.
If Dell refuses to repair this free of charge, I will take it to NSW Fair Trading under Australian Consumer Law (ACL). A motherboard fault that cripples performance from day one is a major failure under ACL. Warranty status does not excuse a defective product that has never performed to spec since purchase.
I have been suffering with this laptop for 4 years, thinking its poor performance was normal. Now I have hard evidence from Cinebench benchmarks, HWInfo throttle reason logs, BIOS confirmations, and multiple hardware defects that all point to a faulty motherboard and poor build quality.
Dell must replace the system board at no cost.
Screenshots Below (Evidence)
HWInfo64 Limit Reasons → shows CPU 100% limited by PL1, no thermal/PROCHOT.
HWInfo64 CPU Package Power → stuck at ~8–12 W under load vs designed 28 W.
Cinebench R23 results → ~667–1238 vs expected 5000–6000
CPU Power vs Power Limits During Cinebench Run
- The blue line = CPU Package Power (stuck around 8–9 W).
- The dashed lines = PL1 (~8 W) and PL2 (~18.8 W) enforced by the Embedded Controller.
- This proves the CPU is being clamped far below its designed 28 W / 51 W limits.- CPU Usage vs Power Draw During Cinebench Run
- Orange line = CPU usage (scaled down so it fits the graph, but clearly near 100%).
- Blue line = CPU package power (~8–9 W).
- This shows the CPU was under full workload, yet power never went above ~9 W — a clear sign of board-enforced throttling.
ejn63
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August 29th, 2025 12:47
Before you start blaming the system board, has the system had a thorough internal cleaning and replacement of the thermal pads? Dust and deterioration of the thermal paste is likely on a system that's been in use for 4.5 years.
As for the construction quality, you'll find that any system sold at this price level is built down to that price -- you don't get robust construction on a system whose price starts in the $500 range brand new.
Maherdeep Dhinjan
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August 29th, 2025 13:16
Also additional things I forgot to add in the message above:
Other Troubleshooting Already Done
I have already updated all BIOS and chipset drivers to the latest, reinstalled Windows(MULTIPLE TIMES), and completed every troubleshooting step Dell support and Google recommended. I also ran Dell’s own ePSA diagnostics (F12 at boot), which it only reported a battery problem stating "battery is nearing its end of its usable life" (or something along those lines of that). Yet Cinebench and HWInfo clearly prove there is severe throttling. This confirms the issue is not related to software, drivers, or Dell’s own diagnostic blind spots — it is purely a hardware fault in the motherboard power delivery/EC.
Impact on Daily Use
This throttling doesn’t just show up in benchmarks — it ruins even the simplest day-to-day tasks. Opening a few Chrome tabs, switching between apps, or running a Zoom call is enough to make the whole laptop stutter and choke. Trying to run small games or complete school assignments feels like a struggle, because the system lags like it’s a cheap, outdated machine from 10 years ago, instead of the i7 laptop I paid extra for.
It’s also embarrassing in front of others as my laptop has shiny Intel i7 11th Gen and NVIDIA stickers on it, advertising “high performance” and reliability because of the brand. People see that and expect it to be both fast and dependable. But when they use it or even just watch me, it slows down badly and constantly runs into issues.
It also gets worse during group assignments as classmates often want to rely on my laptop because specs and assumed reliability. But once they actually try or witness, they quickly realise it underperforms to the point where they could have done it faster on their lower end machines. It never performs to their satisfaction, and I’m left embarrassed again, having to explain why a Dell laptop with good specs can’t handle basic tasks that cheaper models manage with ease.
The performance is unacceptable and makes the machine nearly unusable.
Maherdeep Dhinjan
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August 29th, 2025 13:21
@ejn63
I’ve already opened the laptop multiple times and done a full internal clean. The vents and fans have been thoroughly cleaned, and I even repasted the CPU with high-quality thermal paste. Temps stay stable (65–70 °C under load), and HWInfo clearly shows there is no thermal throttling. The issue is purely PL1 power-limit throttling (8–12 W cap), which is enforced by the EC/board — not a cooling issue.
I get that Vostros are not premium machines, but that doesn’t excuse weak external build quality and a motherboard fault that cripples performance. Even budget systems should be fit for purpose and able to perform at their rated specs. My sister’s older Vostro actually has better build quality than mine, and despite a worse battery, it never had issues like this. That highlights how my unit in particular is defective, not just “cheap construction.”
ejn63
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August 29th, 2025 15:54
If the system is under warranty, which is unlikely - contact Dell for repair. If it's out of warranty, you can either obtain a repair estimate from Dell or from whatever repair shop you'd like.
They're not going to allow a free repair on a system that's out of warranty, whatever the cause is -- whatever performance issues you're claiming would have had to be addressed under warranty.
Maherdeep Dhinjan
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September 1st, 2025 12:19
@ejn63, Hi
I understand your point regarding out-of-warranty systems, but I want to clarify that this is a persistent hardware/firmware issue that has existed since I purchased this Dell Vostro 14 5402.
The CPU frequently underperforms, rarely reaching expected turbo speeds, and drops below base frequency under light load, which is not normal behavior for this model.
I have performed factory resets, clean Windows installs, BIOS updates, and driver installations, so this is not a software or driver issue.
Temporary improvements from unplugging and re-plugging the charger demonstrate that this is not solely related to the battery, and even a new battery would not guarantee a resolution.
Diagnostics, Cinebench tests, and SupportAssist reports confirm inconsistent CPU performance, indicating the issue likely stems from the system’s hardware or firmware.
I am requesting Dell take responsibility for this pre-existing defect, which affects the system’s reasonable performance. While I understand warranty limitations, under Australian Consumer Law, I am entitled to a system that functions as reasonably expected at the time of purchase.
I would like Dell to provide a fair resolution, rather than dismissing the problem due to warranty status.
Thank you,