How Know Your Buy checks a laptop
Know Your Buy runs a set of short tests on the laptop, explains each result in plain words, and then gives one verdict. Here's what every test does and what a bad result means for you.
Run All takes about 8 minutes
Press Run All and the tests go one after another, so one test's heat doesn't spoil the next. You can also run any test on its own.
- 1BatteryFirst, because it asks you to unplug the charger.
- 2FanWhile the laptop is still cool, to get a resting fan speed.
- 3Processor benchmarkAbout 25 seconds, on a cool processor so the score is fair.
- 4Processor60 seconds at full load.
- 5Graphics60 seconds per graphics chip.
- 6MemoryUp to about 2 minutes.
- 7StorageLast, because it needs the drive to itself.
Battery
What it looks at
How much charge the battery holds now compared with when it was new, and how many charge cycles it has done. Know Your Buy reads this from Windows and from the Windows battery report, and compares the two.
What counts as a problem
- 80% or more of its original charge: fine.
- 50–79%: worn. You'll get noticeably less time away from the plug.
- Under 50%: badly worn. Plan to replace it.
What it means for you
You get an estimate of real hours of use and, when the battery is worn, a typical replacement price to take off the asking price.
- Time
- Under a minute
- How sure the result is
- Lower when Windows and the battery report disagree. That usually means the battery's own chip is miscalibrated.
Storage (SSD or hard drive)
What it looks at
The drive's health counters (SMART) and its real read and write speed. The write test uses at most 1 GB of free space, scaled down when the drive is nearly full, and deletes the file straight after.
What counts as a problem
- The drive reports that its own health check failed.
- Bad or unstable sectors, unreadable sectors or media errors.
- 90% or more of its rated write life used, or spare blocks nearly gone.
- Slow reads: under 1,000 MB/s for NVMe, 400 MB/s for SATA SSD, 60 MB/s for a hard drive.
What it means for you
A failing health check means the drive expects to die and data is at risk. Wear or slow speeds mean it's on its way and worth negotiating over.
- Time
- About a minute
- How sure the result is
- Some drives don't expose every counter to Windows. When counters are missing, Know Your Buy judges from speed and says so.
Processor
What it looks at
A single-core and multi-core benchmark score, then 60 seconds at full load on every thread while Know Your Buy watches each core's temperature and speed and checks every calculation.
What counts as a problem
- Any calculation error: the processor or memory is unstable.
- 95 °C or hotter under load.
- Slowing down by more than 20% under load.
What it means for you
Calculation errors are a serious fault. Heat and slowdown usually mean dust or dried thermal paste: a cleaning and fresh paste costs roughly ₹500–1,500 at a local shop.
- Time
- About 1.5 minutes, including the benchmark
- How sure the result is
- Exact core temperatures need a small driver called PawnIO, which Know Your Buy offers to install. Without it, Know Your Buy judges slowdown from measured work speed instead.
Graphics
What it looks at
Every graphics chip in the laptop, built-in Intel or AMD and separate AMD or NVIDIA, runs a compute test that checks its own answers.
What counts as a problem
- Stops responding under load.
- Returns wrong results: faulty graphics chip or video memory, often seen as screen glitches.
- Can't start the test: driver problem or faulty chip.
- 90 °C or hotter.
What it means for you
Wrong results or freezing are serious. Heat means the cooling needs cleaning.
- Time
- About 60 seconds per graphics chip
- How sure the result is
- Some graphics chips, often Intel, don't report a temperature to Windows.
Memory (RAM)
What it looks at
Writes test patterns across free memory and reads them back to make sure nothing changed.
What counts as a problem
- Any mismatch between what was written and what was read back.
What it means for you
Faulty memory causes random crashes and corrupted files. This is a short test: it catches most bad RAM but not every rare fault a multi-hour test would.
- Time
- Up to about 2 minutes
- How sure the result is
- Results show how many patterns ran in the time allowed.
Fan
What it looks at
The fan speed at rest and under load.
What counts as a problem
- The fan doesn't spin under load: dead or stuck.
- It speeds up by less than 20%: may be failing.
What it means for you
A dead fan means the laptop will overheat. A replacement fan usually costs about ₹800–2,500.
- Time
- Short, right after the battery check
- How sure the result is
- Many laptops hide their fan from Windows. On those, the Fan check is skipped and the processor test's heat and slowdown readings cover cooling instead.
Stress test
What it looks at
Every processor thread and every graphics chip at 100% at the same time, while Know Your Buy watches temperatures, speeds, power and fans. It asks before it starts.
What counts as a problem
- Errors or freezing: unstable under heavy use. Expect crashes in games or editing.
- Overheating, slowing down by more than 25%, or a dead fan: cooling can't keep up.
What it means for you
This is harder than any real app. A healthy laptop gets hot (80–90 °C is normal) and loud, but keeps its speed and makes no errors.
- Time
- 1, 3 or 5 minutes, your choice
- How sure the result is
- Same sensors as the processor and graphics checks.
Specs
What it looks at
Model, processor, graphics, RAM size and speed, and every drive with its type (NVMe, SATA SSD or hard drive) and size.
What it means for you
Check these against the listing. If the seller said 16 GB and Specs shows 8 GB, ask why.
- Time
- Instant
- How sure the result is
- Read directly from Windows.
Confidence levels
Laptops don't always report their numbers well, and some counters can be reset. So every result says how sure Know Your Buy is.
- High
- Measured directly, and the sources agree.
- Medium
- Measured, but from a less direct source, or one sensor was missing.
- Low
- The laptop didn't report enough to be sure. Double-check this part yourself.
How the verdict is decided
Know Your Buy scores each part, then applies three plain rules, in this order.
Walk away
If the processor, graphics, memory, storage or stress test fails outright: calculation errors, freezing, memory errors or a drive that reports it is failing. These parts are expensive or impossible to replace.
Negotiate
If anything else shows a warning, like heat, slowdown, a worn drive or a weak fan, or the battery is under 60% health, or the hardware is old and low-end overall.
Buy
If none of the tests that ran found a fault.
What it's good for
Separately, Know Your Buy rates the laptop Good, Okay or Bad for each use, based on what that use needs:
- College & office
- 8 GB RAM or more and an SSD. Battery matters.
- Coding
- 16 GB RAM, an SSD and a faster processor.
- Video editing
- 16 GB RAM, an NVMe SSD, a fast processor and decent graphics.
- Gaming
- 16 GB RAM and strong graphics. Graphics is the deciding part.
Not covered yet: screen, keyboard, speakers and ports. The buyer's guide has a quick manual checklist for those.