What Was Happening
A customer from Clapham SW4 brought in an HP Pavilion 15 that had been slow for over a year. Boot time had grown to approximately four minutes. The machine frequently froze for 10–20 seconds during normal tasks — opening a browser tab, switching between windows, saving a document. The base of the laptop ran very hot even during light use, and the fan ran constantly at high speed.
The customer had tried a Windows clean install the previous year, which had improved things briefly before the same problems returned. They wanted to understand what was actually causing the slowness before spending money on a replacement machine.
Our Diagnosis
We ran a full health check covering thermal performance, drive health, memory, startup load, and background processes.
Thermal: Temperature monitoring under a controlled load showed the CPU reaching 97°C within 40 seconds — two degrees below its shutdown temperature. Inspection of the cooling system found the heatsink fins heavily blocked with compacted dust. The laptop had been used in a studio flat in a Georgian conversion near Clapham Common for five years — exactly the environment where cooling systems block faster than normal due to limited room airflow.
Drive health: SMART data from the 1TB conventional hard drive showed a reallocated sector count of 47, with a pending uncorrectable sector count increasing. This is an unambiguous warning that the drive was in the early stages of physical degradation. The customer had no backup.
Startup queue: Windows Startup Manager showed 22 items loading at boot. Nine of these were from applications the customer had uninstalled, but whose startup registry entries had not been cleaned up. Several others were from software running background update services — for applications the customer confirmed they had not opened in over a year.
Memory: 8GB RAM, tested and healthy. Not a contributing factor.
The picture was clear: three separate problems operating simultaneously, each making the others worse. A throttled CPU from overheating slows everything. A failing conventional hard drive slows read/write operations further, making the already-throttled CPU appear even slower. And 22 startup items loading on every boot extend startup time while the system is at its most thermally stressed.
How We Fixed It
We discussed all findings with the customer and provided a written report before starting any work. The customer approved the following:
Cooling system clean: Full teardown to access heatsink and fan. Heatsink fins cleared completely. Fan blades and housing cleaned. Thermal paste replaced — the original paste had dried to a powder-like consistency after five years.
Drive replacement: The failing conventional hard drive was imaged before removal. The image was verified for integrity, then transferred to a replacement 500GB SSD. The size reduction from 1TB to 500GB was discussed with the customer beforehand — total data used was 280GB, making the 500GB SSD adequate with meaningful headroom.
Startup rationalisation: The startup queue was reduced from 22 items to 7. Nine abandoned entries were removed from the registry. Six active-but-unnecessary services were disabled. The three items the customer confirmed they needed (OneDrive, a VPN client, and an antivirus) were retained.
The Result
Post-repair testing showed CPU temperatures peaking at 68°C under the same controlled load that had previously driven the machine to 97°C. Boot time measured at 28 seconds — down from four minutes. The machine ran stably through an extended test period without freezing. The drive failure risk had been eliminated and data was backed up.
The customer collected the machine on day two, with a written report covering all findings and what was done.
Why These Three Problems Compound Each Other
Each of these faults is manageable on its own. Together they create a machine that appears to be broken beyond economic repair.
A slow boot from startup overload is a nuisance. A slow boot combined with a thermally throttled CPU running at 20% of its designed speed means Windows is initialising those 22 startup items at a fraction of the speed it should be, making a 2-minute boot into a 4-minute one.
A failing conventional hard drive is slow to read under normal conditions. When the CPU is also throttled, every disk read takes longer. The combination makes even opening File Explorer feel like a significant operation.
Understanding that these problems interact — and addressing all of them — is what a health check is for. Replacing only the drive without cleaning the cooling system would have resulted in a machine that booted faster but still ran slowly under load.
Prevention Tips
- Back up regularly — a drive showing SMART warning signs gives you a window to act, but that window is not predictable in length
- Review Windows startup items once a year via Task Manager → Startup Apps, and disable anything you do not use regularly
- Use the laptop on a hard surface with clear rear vent access; in a compact flat, this matters more than it does in a larger space with better natural airflow
- If your laptop runs hot and the fan is loud during light tasks, the cooling system needs attention — do not wait for performance problems to become severe before acting
Local Help in Clapham SW4
We offer PC and Mac health checks at our Putney workshop for customers across Clapham SW4 and SW11. Free collection means you don’t need to deal with the parking around Clapham Junction. Health checks include a written plain-English report covering all findings.
Related Services
- PC & Mac Health Check — full diagnostic service for any laptop or desktop
- PC & Mac Health Check in Clapham — local service for SW4 and SW11
- SSD Upgrade — replace a slow or failing drive with solid-state storage
More Case Studies
- PC & Mac health check — slow MacBook in Wandsworth — health check on an Apple machine with overlapping causes
- Laptop overheating and thermal throttling repair in Clapham — cooling system repair on a similar HP laptop
- Compaq Presario hard drive replacement in Wandsworth — drive failure case from a nearby area