Performance, RAM & thermals
Confirm the laptop has the chips it claims, that the memory is healthy, and that it doesn't overheat and throttle under load — the classic "fast on paper, slow in real life" trap.
Verify CPU, RAM & GPU specs Important
Fastest built-in check — Settings → System → About, or run the DirectX diagnostic:
dxdiag
dxdiag lists the CPU, RAM, and both the System and Display tabs show the graphics chip. For exact RAM speed and slot usage, run CPU-Z (cpuid.com) → Memory & SPD tabs.
- CPU model matches the listing (e.g. "Core i5-1235U", not a weaker chip).
- RAM amount is correct, and note if slots are upgradable (CPU-Z SPD tab shows empty slots) or soldered.
- GPU: integrated vs. the dedicated card promised.
Compare what you see against the maker's spec for that serial (from Stage 1). Downgraded RAM or a swapped-in weaker drive is a common trick.
Can you upgrade the RAM & storage later?
For a budget buy, upgradeability is a big plus. In CPU-Z's SPD tab, an empty memory slot means you can add RAM later; if both slots are full or the RAM is soldered (common in thin laptops), you're stuck with what's installed. Most laptops still let you swap or add an M.2 SSD cheaply. If unsure, search "your model RAM upgrade" before buying.
Test the memory (RAM) Important
Bad RAM causes random crashes and blue screens. A quick built-in test (note: it requires a restart and a few minutes, so do this near the end):
mdsched
Choose "Restart now and check". It runs before Windows loads and reports any errors after reboot. If you're short on time, even the Standard pass catches most faults.
Want a deeper memory test?
The built-in test is plenty for a quick buy. For an exhaustive check (if you have time and a spare USB stick), MemTest86 boots from USB and scans the RAM thoroughly — but it can take 30+ minutes, so it's usually overkill during a sale.
Short stress test for heat & throttling Critical
This is where overheating and a tired cooling system show themselves. Keep the charger plugged in for max performance.
- Open HWiNFO (hwinfo.com) in "Sensors only" mode, or HWMonitor (cpuid.com). Note the idle CPU temperature (usually 35–50 °C).
- Load the CPU for ~5 minutes. HWiNFO has a built-in stress option — or create a real load with several browser tabs plus a 4K video. (Idle browsing won't reveal a cooling problem; you need sustained load.)
- Watch CPU temperature and clock speed together.
| Under load | Reading | Verdict |
|---|---|---|
| Peak temp | Up to ~85–90 °C briefly | Normal for laptops |
| Sustained temp | Pegged at ~95–100 °C | Cooling needs service |
| Clock speed | Holds near rated boost | Healthy |
| Clock speed | Drops far below base & stays there | Thermal throttling |
- Listen to the fan — it should ramp up, then settle. Grinding/rattling means worn bearings; no fan noise under heavy load can mean a dead fan.
- Feel the airflow at the vents — warm air should be moving.
Hitting 100 °C and dropping clocks under load usually means dust-clogged fans or dried thermal paste — a cheap-ish service, but factor it into your offer.
GPU check If applicable
- Confirm the dedicated GPU appears in Task Manager → Performance and in
dxdiag. - For a quick visual/thermal load, play a 4K video or a short browser-based 3D demo while watching GPU temp in HWiNFO.
- Look for artifacts — flickering, strange colours or glitches on screen under load can mean a failing GPU.
Open Task Manager → Performance at idle too: CPU/RAM/disk usage should be calm. A laptop pinned at 100% disk or CPU while "doing nothing" hints at a struggling drive or background problems.