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Measure it, then fix it.

One question each, end to end: what the symptom looks like, what it means, and what to change next.

Hardware guides, from symptom to fix

These 48 guides each answer one hardware question end to end: what the symptom looks like, how to measure it with the free browser stress test, and what to change once you have the number. They cover thermal throttling, telling a processor limit from a graphics one, reading a benchmark result honestly, improving sustained performance, and how path tracing works.

The guides sit between the other parts of the site. The fix articles start from a single complaint, such as a laptop that is slow on battery, and rank its causes; the diagnosis pages explain what the test shows for each symptom; the glossary defines every term a guide uses; and the methodology page sets out what each stage of the test measures. A guide is the place to understand the idea, and the test is the place to see it on your own machine.

Every guide here starts from something a machine is doing that you can see, and ends with something you can change. None of them ask you to install a monitoring suite first, and none of them recommend a hardware purchase as the opening move: most sustained-performance problems on a laptop are a cooling or power-limit problem, and several of those are free to fix.

The order they are worth reading in depends on the symptom. If the machine is fast and then slowly stops being fast, start with thermal throttling. If you are trying to work out whether the processor or the graphics card is holding a game back, start with the bottleneck guide. If you already have numbers from somewhere and want to know whether the difference between two of them is real, start with reading benchmark results.

Each guide says plainly what a browser-based measurement can support and what it cannot. Temperatures, fan speeds and power draw are not readable from a web page on any browser, so where a cause is named it is inferred from the shape of a throughput curve, with the confidence that inference deserves.

Good places to start

Run the free test
[Guide]

Memory latency vs bandwidth: what a random-walk test shows

Bandwidth is how many bytes memory moves per second; latency is how long one dependent load waits. How SystemCheck measures each and what they cannot say.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Single-thread vs all-thread memory bandwidth

Why SystemCheck measures memory bandwidth on one thread and then on several, what the ratio between the two shows, and what it cannot prove.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

What "not measured" means in your report

When a stage cannot run or its data cannot be trusted, SystemCheck says not measured and gives the reason instead of estimating a number.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Reading the confidence interval on every figure

Each headline figure in a SystemCheck report carries an interval: the spread inside that one run. How it is computed, what it covers and what it does not.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Is 80C safe for a CPU? What a browser can tell you

Whether 80C is safe depends on the chip's own limit, which its maker publishes. Why a browser test cannot read temperature and what it measures instead.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Mac in Safari: why only 8 threads show

Safari reports at most 8 logical processors to a web page on a desktop, so a browser test there runs at most 8 workers. What that means for your figures.

SystemCheck · 4 min read · updated 29 October 2026

[Guide]

Is a browser stress test as good as Prime95 or Cinebench?

A browser test and a native tool answer different questions. What SystemCheck measures, what native tools do that a page cannot, and when to use which.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Why a PC slows down over time, and how to tell which kind

A PC that feels slower after months or years is usually carrying more software, less free space, or a cooler that has lost ground. How to tell which.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

How to check a used laptop before you pay

A short, in-person check for a used laptop: what to look at, what to plug in, and a 3-minute browser stress test that shows whether it holds up.

SystemCheck · 5 min read · 5 steps · updated 29 October 2026

[Guide]

PC specs and performance: what a test's numbers mean

Specs say what a PC is built from; a performance test says what it delivers under load. How to read SystemCheck's figures against the spec sheet.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

GPU stress test: how long is long enough?

Long enough for the card to settle, and long enough to repeat. What SystemCheck's GPU stage lengths are, and when a longer run is worth it.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

How to benchmark a PC for gaming without installing

Three browser checks that say something about gaming: whether the GPU holds its level, whether frames arrive evenly, and whether the CPU keeps up.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Frame pacing vs FPS: why smooth is not the same as fast

FPS counts frames per second; frame pacing is whether they arrive evenly. Why 60 FPS can stutter, and how SystemCheck's pacing test measures it.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

How to reduce a GPU bottleneck once you have measured it

Your graphics card sets the ceiling. What to change first: resolution, render scale, the heaviest settings, the power mode, and which GPU the game runs on.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

What CPU throttling means, read off one chart

CPU throttling is the processor lowering its speed to stay inside a heat or power limit. How it looks on a throughput chart, and what a chart cannot show.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

What the WebGPU compute test measures, and what it does not

SystemCheck's WebGPU compute test times a shader of dependent multiply-adds and a buffer copy on your GPU. What the GFLOP/s figure means and its limits.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Testing an SSD's sustained write speed in a browser

Many SSDs write fast until a cache fills, then slow down. How SystemCheck's sustained write test finds that point from a browser, and what it cannot see.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Responsiveness test: input delay your PC adds under load

A PC that feels sluggish while busy is late to answer input. How SystemCheck's responsiveness test measures that delay idle and under load, with its lines.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Recovery test: how fast a machine comes back after load

After heavy work, a machine needs time before it can boost again. How SystemCheck's recovery test measures that after a short idle break, in its own units.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

How to document laptop throttling for a warranty claim

A warranty desk wants evidence it can check. What to record about a throttling laptop, how a fingerprinted report helps, and what a browser cannot prove.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Before and after: measuring a repaste or a fan clean

Whether new thermal paste or a fan clean helped is a measurement. How to run a fair before and after test and read the difference against noise.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Online exam system check: what each check actually tests

Before a proctored exam, the camera, microphone, connection, screen and browser are checked. What SystemCheck's exam profile tests in each, and its limits.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

The webcam, microphone and connection lines we use for calls

The lines SystemCheck's video call check applies to webcam frame rate, audio delay, upload and jitter, where each comes from, and which are starting values.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Battery or plugged in: what changes in a laptop's run

A run on battery and a run plugged in measure two different machines. What our validation laptop showed, why the report flags it, and how to test yours.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Heat, a power limit or a busy machine: what a curve shows

A slowing curve can come from heat, a power budget ending or another program. What each looks like, what a run can detect, and what needs a sensor log.

SystemCheck · 7 min read · updated 29 October 2026

[Guide]

Bufferbloat: why your ping rises when the line is busy

Bufferbloat is latency that climbs when the line is busy. How it is measured and graded, why upload is usually worse, and the router setting that fixes it.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Jitter: what an uneven ping does to calls and games

Jitter is how much the delay changes from one packet to the next. How it is measured, how it differs from ping and spread, and what lowers it at home.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Bluetooth headphone delay: measure it, then cut it

Bluetooth headphones buffer sound before they play it. How to measure the delay you hear, how much the wireless link adds, and what brings it down.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Check 5.1 and 7.1 surround on Windows and macOS

Most surround tests pan stereo. How to set Windows or macOS to 5.1 or 7.1, check each real speaker one at a time, and fix silent or swapped channels.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

Is hardware acceleration on? A check for each browser

With acceleration off, the processor draws everything. How to tell if your browser uses the graphics chip, and the switch in Chrome, Edge, Firefox and Safari.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

WebGPU vs WebGL: what each is and which one you have

WebGL and WebGPU are two ways a web page reaches the graphics chip. How they differ, which browsers have WebGPU, and what not supported or no adapter means.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

sRGB, Display P3 and Rec. 2020: what a browser can tell

A browser can read which colour gamut it is given and show colours past sRGB for your eyes. It cannot measure your panel's coverage, and why that matters.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

How to find your mouse's real DPI

A mouse's DPI setting names counts per inch. How to measure the real figure with a ruler or a bank card, why it can differ, and how much error to expect.

SystemCheck · 5 min read · updated 29 October 2026

[Guide]

How to check if your GPU decodes AV1 in hardware

Whether AV1 plays on the graphics chip or the processor decides smooth 4K and battery life. How to ask the browser, and how to measure the decode speed.

SystemCheck · 6 min read · 3 steps · updated 29 October 2026

[Guide]

How much VRAM can a browser use, and why not all of it

A web page cannot see your card's VRAM, only what the browser lets it allocate. How that is measured, why it is smaller than the total, and what it is for.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

Can my laptop run a local LLM? The memory arithmetic

Whether a local model runs starts with memory: parameters times bytes per weight. The formula, what quantisation changes, and what it leaves out.

SystemCheck · 7 min read · updated 29 October 2026

[Guide]

How to spot a fake USB drive or SD card

A fake drive reports more space than it has and loses what you write past the real size. Why the properties window cannot tell, and the check that can.

SystemCheck · 6 min read · 3 steps · updated 29 October 2026

[Guide]

How long will my laptop battery last under load?

Battery life depends on the load, so measure it under yours: percent an hour from the charge level, and why any runtime figure is an estimate.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

What controller polling rate means, and what a browser sees

Polling rate is how often a controller reports. What the Hz figure means in milliseconds, why Chrome's Gamepad API tops out near 250 Hz, and how to see more.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

What resolution is my webcam really sending?

A camera can offer 1080p and send 720p, or promise 30 fps and deliver 15. How to count what arrives, and what a call app on your computer would send.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

What a reaction time test actually measures

Every online reaction test times you plus your screen, mouse and browser. What each adds, which parts a page can measure, and what only hardware can.

SystemCheck · 6 min read · updated 29 October 2026

[Guide]

How path tracing works, from one ray to a finished image

Path tracing follows light backwards from the camera, bouncing at random until it finds a light. How noisy samples become a clean image, and why it costs.

SystemCheck · 7 min read · updated 16 September 2026

[Guide]

Path tracing vs ray tracing: what the difference actually is

Ray tracing in games adds one effect to a normal image. Path tracing computes all the lighting from bounce paths. What each costs, and how to test your card.

SystemCheck · 6 min read · updated 16 September 2026

[Guide]

How to diagnose and fix thermal throttling

Diagnose thermal throttling by measuring throughput decay under sustained load, then fix it with airflow, paste, fan curves, and power limits.

SystemCheck · 9 min read · 8 steps · updated 29 October 2026

[Guide]

How to read a benchmark result without fooling yourself

A single benchmark number hides variance and decay. How to read peak versus sustained, judge run-to-run spread, and know when a result is not evidence.

SystemCheck · 8 min read · updated 29 October 2026

[Guide]

How to tell whether your CPU or GPU is the bottleneck

Identify the limiting component by watching which one saturates first. A practical method using resolution scaling, utilisation, and frame-time behaviour.

SystemCheck · 8 min read · 7 steps · updated 14 September 2026

[Guide]

How to improve sustained performance, not just peak scores

Peak scores are won in the first ten seconds; real work happens in the plateau. A practical method for raising sustained throughput on an existing machine.

SystemCheck · 9 min read · 8 steps · updated 12 September 2026

[Guide]

How accurate is a browser benchmark, really?

An honest account of what a browser-based benchmark can measure reliably, what it cannot measure at all, and when you should use a native tool instead.

SystemCheck · 10 min read · updated 12 September 2026

Questions

  • It depends on the symptom. If the machine is fast and then slowly stops being fast, start with thermal throttling. If you want to know whether the processor or the graphics card holds a game back, start with the bottleneck guide. If you already have two numbers and want to know whether the difference is real, start with reading benchmark results.