AutoCAD slowing down mid-render — a thermal story
The site architect’s HP ZBook Power G10 had been the primary workstation for a significant residential project in Banjara Hills — a multi-level basement excavation and RC frame construction spread over 18 months. The laptop had been on-site daily: concrete dust in the air, intermittent monsoon humidity, and the general particulate environment of active construction. The complaint when it arrived at the bench was specific: AutoCAD 3D render tasks that previously completed in 6–8 minutes were now taking 12–15 minutes, with the laptop’s fan running at maximum speed from the moment the render started and the base plate becoming hot enough to be uncomfortable to touch.
Bay 3 thermal camera: the evidence before disassembly
Thermal scan under load
We ran a standardised thermal stress test (Prime95 + GPU Furmark simultaneously) with the thermal camera observing the base plate. The CPU zone showed 97°C within 90 seconds of load start — well past the Intel Core i7-13800HX’s thermal throttling threshold of 100°C. The VRM zone (the area directly behind the CPU socket on the ZBook’s motherboard layout) showed 103°C, confirming that the shared heatsink was not carrying heat away from either the CPU or the VRM effectively. The exhaust vent airflow, measured with a handheld anemometer, was 0.8 m/s — a severely clogged baseline versus the expected 2.5–3.0 m/s for a clean ZBook under the same load.
Inside the chassis
With the base removed, the internal state was immediately apparent. The heatsink fins were packed solid with grey-white concrete particulate — not the fluffy grey lint of normal office dust, but a dense crust that had to be scraped rather than blown clear. The fan blades showed abrasion wear on all three blades, consistent with months of rotation against fine silica particles. The VRM thermal pads — the soft compressible material that fills the gap between the VRM MOSFETs and the heatsink plate — had compressed to approximately 40% of their original 1.0 mm thickness, meaning there was an air gap between the VRM and the heatsink for the majority of the contact area.
The repair: deep clean and thermal refresh
Clean sequence
The heatsink assembly was removed and cleaned in a three-step sequence: compressed air to dislodge bulk material, IPA-soaked swabs to dissolve the silica/calcium crust from between the heatsink fins, and a final compressed air pass to clear the dissolved residue. Fan blades were cleaned individually. The CPU die and GPU die surfaces were cleaned of dried thermal paste using thermal paste remover. The VRM area was cleaned of old thermal pad remnants.
Thermal refresh
New Honeywell PTM7950 phase-change thermal compound was applied to the CPU and GPU dies. New 1.0 mm silicone thermal pads (3 W/m·K) were cut to size and applied to all VRM MOSFET packages. Reassembly and post-clean thermal test: CPU max under the same stress test load: 68°C. VRM max: 74°C. Exhaust airflow: 2.7 m/s. AutoCAD render time for the same DWG file: back to 6 minutes 40 seconds. Invoice: deep clean + thermal refresh + fan inspection: ₹3,200. For related laptop overheating repair and internal cleaning service, see our pages.