Start with the dead pixel test Step one of six. Open the other five in tabs first.
On this page
Photos of a used monitor show a lit screen, and a lit screen hides most of its faults. Dead pixels, a glowing corner or the ghost of someone’s taskbar only show up when you put the right image on it.
This page gives you a fixed order for that. It chains six full-screen tests from our own tool pages, about ten seconds each, and ends in a checklist you can tick on your phone or print. It works in a driveway, at a pickup point or at your desk on the day a parcel arrives.
The 60-second test sequence
Plug the monitor into your laptop, set it to its native resolution and open each tool full screen. Ten seconds a test is enough to catch the obvious faults. The minute covers looking only, so do the cable and setup first.
| Step and test | What to do | Walk away or haggle if |
|---|---|---|
| 1. Dead pixel test | Step through every color. Scan the whole screen from your normal seat, then look at the center up close. | A dot stays on every color, or two dots sit close together. Our return policy page lists the ISO counts, but a private sale has no return window, so your own tolerance is the limit. |
| 2. Backlight bleed test | Black screen, dim room, brightness at your normal level. Look at the edges and corners, then move your head left, right, up and down. | Bright patches stay put as you move. Glow that shifts or fades with your angle is IPS glow and is normal. OLED has no backlight, so skip this step on OLED. |
| 3. Color and uniformity test | Flat gray first, then the gradients. | A dark patch or a tint on flat gray, or hard bands in a smooth gradient. Uniformity varies between units, so only a clear patch counts. Hard bands often point to a color depth or picture-mode setting, so check those before blaming the panel. |
| 4. Burn-in test | Gray, white and the solid colors, then the retention check. Look where static things live: the taskbar, toolbars and the bottom edge. | A faint shape shows on every color. Retention fades within minutes and you can’t wait a day in a car park, so any shape you can see on a used OLED is a reason to walk or take money off. |
| 5. Ghosting test | Watch the moving shape on the dark, mid and light backgrounds. Try one overdrive step up or down before you judge. | A dark trail behind the shape is ghosting and a bright halo is overshoot. Both can come from the overdrive setting, so change that first. A trail you can’t tune away is the panel. |
| 6. Refresh rate test | Run it over the cable and port you’ll use at home. | The number should match what the monitor is sold at. 60 on a faster monitor usually means the setting, the cable or the port. Swap the cable before you walk. |
Two caveats. A browser test shows what the browser draws, so a fault that only appears on one input needs the same port you’ll use at home. And a phone photo makes bleed and glow look worse than your eye sees them, so judge by eye.
What to bring
- A laptop and its charger, with a video output that matches the monitor.
- A video cable you trust, and a spare.
- A dry microfiber cloth. Dust looks like a dead pixel until you wipe it.
- Your phone with the six test pages open in tabs, and this checklist.
- Headphones or a USB stick to try the headphone jack and USB ports.
Printable used monitor checklist
Tick items as you go and the count updates. Print gives you a clean one-page sheet in black on white, whatever theme this page is in. Nothing you tick is saved or sent anywhere.
Used monitor checklist
Before you go
Look and touch, screen off
Ports and cables
The six tests, about ten seconds each
Seller and money
Where you buy sets your protection
The same fault is a refund in one place and your problem in another. We read each page below in October 2026, and the right-hand column is our reading of what it means.
| Where you buy | What the page says | What it means for you |
|---|---|---|
| Private sale, in person | Your Europe says goods bought from a private individual, as is often the case with online auctions, aren’t covered by EU consumer rules.Source: Your Europe: guarantees FAQ, checked Oct 2026. | Treat a pickup deal as final and run the tests before you pay. We couldn’t open a Facebook Marketplace buyer-protection page to cite, so we say nothing about it. |
| eBay | The Money Back Guarantee covers an item that doesn’t match the listing or is faulty or damaged. You have to pay through eBay checkout: payments completed outside eBay, such as bank transfer or cash, aren’t covered. A return request is open until 30 days after delivery or the seller’s stated window, whichever is longer. An item returned used or damaged can have its lost value deducted. Items sold as not working or for parts only are covered too, but with a shorter window: if the seller doesn’t offer returns, you must request a return no later than 3 calendar days after the estimated or actual delivery date.Source: eBay Money Back Guarantee policy, checked Oct 2026. | In our reading, a dead pixel in a listing that said “no defects” is a not-as-described case. Test on delivery day and repack it in the box it came in. |
| Amazon (US) | Most items can be returned within 30 days of delivery. Select Amazon Renewed products in Acceptable, Good or Excellent condition get 90 days, and Premium condition gets 365. When a third-party seller ships its own stock, your return goes back to that seller. Amazon adds that a manufacturer warranty may not cover used products offered on Amazon.com.Source: Amazon.com: return policy, checked Oct 2026. | Check who sells it and which condition grade it carries. Read the warranty line on the product page before you assume the brand will cover it. |
| Best Buy (US) | The return period applies to new, clearance, open-box, refurbished and pre-owned products shipped from and sold by Best Buy: 15 days, or 60 for My Best Buy Plus and Total members. The longer window doesn’t apply to Marketplace sellers.Source: Best Buy US: return and exchange policy, checked Oct 2026. | An open-box or pre-owned monitor from Best Buy runs on the same clock as a new one. Use those days to run all six tests at home. |
Warranty is a separate question. AOC’s US and Canada warranty is written for the original consumer, and its 90-day EASE warranty is non-transferable. A used monitor can carry no warranty at all, so ask the seller what the paperwork says and read the brand’s own page for your model before you pay extra for “still in warranty”.Source: AOC US and Canada: warranty, checked Oct 2026.
OLED burn-in: how many hours is too many?
Nobody publishes a safe number of hours for a used OLED monitor, so you’re reading markers. Two long tests give the best ones.
- RTINGS ran an LG 27GR95QE-B, an Alienware AW3423DWF and a Samsung Odyssey OLED G8 around the clock on a news stream at maximum brightness. By about 24 months all three showed burn-in along the bottom ticker row, and the LG also showed the outline of the centered presenter. That’s a deliberate torture test and nothing like normal use. Tom’s Hardware, 27 September 2025.
- Monitors Unboxed used an MSI MPG 321URX QD-OLED for static productivity apps, around 60 hours a week, and had logged over 6,000 hours at the two-year mark. It showed a faint line down the center, burn-in along the taskbar and the first icon-shaped marks, just visible on some backgrounds. PC Gamer called burn-in real and noticeable, but not catastrophic. PC Gamer, 5 March 2026.
For scale, 8 hours a day for two years is about 5,840 hours. That’s our arithmetic, and it lands near the second test. The estimator below turns a seller’s answers into hours.
Power-on hours estimator
Hours are half of it. In both tests the wear sat where static elements stayed, which is why the burn-in test comes before the money does.
Warranty can matter more than hours. Dell’s monitor support page says QD-OLED panel technology is limited to a 3-year maximum warranty term and that this includes burn-in. We couldn’t find whether that coverage passes to a second owner, so ask Dell with the serial number before you count it as a plus.Source: Dell: Monitor Support Services, checked Oct 2026.
Some monitors can also report their own power-on time. The monitor-control feature list that ddcutil documents includes a read-only “display usage time”, described as active power-on time in hours. We haven’t checked which models fill it in, so treat a number as a bonus if you can read one.Source: ddcutil: vcpinfo output, checked Oct 2026.
Ports and cables
The tests only mean something over the connection you’ll use. Our refresh rate test says 60 Hz on a faster monitor usually points to the Windows setting, the cable or the port, so a low reading isn’t proof the panel is bad. Swap the cable first, then check the setting. If it’s still stuck, the 144Hz showing 60Hz guide goes through the rest.
Look at the back before you plug in. Bent pins, a loose socket or a cable that wobbles are repair costs you’d inherit. Check the ports against the spec sheet for the exact model, and against the ports on your computer.
The original box, cable and stand also make the monitor easier to resell later.
Questions to ask the seller
- What’s the exact model number and serial number?
- How old is it, and do you have the receipt?
- Why are you selling it?
- What did you use it for, and for how many hours a day?
- Does it have dead pixels, marks or settings problems you know about?
- Can I plug in my laptop and run a few screens before I pay?
- Is it still under warranty, and in whose name?
- What comes in the box?
Ask in the listing chat where you can. If an answer changes at pickup, you’ll have the first one in writing.
Warning signs
- The photos show the screen off, or they’re stock images.
- The seller won’t let you plug in, or says it “just needs a cable”.
- The listing says “not working” or “for parts”. On eBay those items sit under special rules.
- The seller wants payment outside the platform. On eBay, a payment completed outside eBay isn’t covered by the Money Back Guarantee.
- The price is far under every other listing for the same model.
- The seller can’t say how old it is, or the answers keep changing.
- A “refurbished” label comes with no warranty terms, and Amazon itself warns that a manufacturer warranty may not cover used products.
When a test fails
Dead pixels and burn-in don’t come back, so they’re a price conversation. A stuck colored dot sometimes clears with the stuck pixel fixer, which makes it a smaller one. A refresh rate or ghosting result is often a setting. Our guides cover each case:
- Stuck pixel on your monitor? How to tell and fix it
- Backlight bleed or IPS glow? How to tell, and when to return it
- OLED burn-in or image retention? How to tell, fix and prevent it
- How to fix monitor ghosting
- 144Hz monitor showing 60Hz? How to fix it
If you’ve already bought a new monitor with a dot on it, that’s a different problem with different rules. Start with the dead pixel return policy by brand and country.
Frequently asked questions
How long does the 60-second test take?
The six looks take about a minute at ten seconds each. Plugging in, setting the native resolution and finding the right cable add a few minutes. We haven’t timed it in a stranger’s garage, so treat the minute as a target.
Do I need a laptop to run the tests?
You need a device with a web browser that can send a picture to the monitor. A laptop with an HDMI, DisplayPort or USB-C output is the simplest choice. Open the six test pages in tabs before you leave home.
Can I return a used monitor if I find a dead pixel later?
It depends where you bought it. eBay’s guarantee covers an item that doesn’t match its listing, and Best Buy’s window covers the pre-owned items it sells. Your Europe says purchases from a private individual aren’t covered by EU consumer rules, and we found no source promising a return on a private cash pickup elsewhere.
Is burn-in covered by warranty on a used OLED monitor?
Dell’s monitor support page says its QD-OLED panels have a 3-year maximum warranty term that includes burn-in. We couldn’t find whether that passes to a second owner, and we haven’t checked other brands, so ask the maker with the serial number.
More from GigaScreens
- Burn-in test
- Backlight bleed test
- Color and uniformity test
- Ghosting test
- Refresh rate test
- All monitor fix guides
Sources
- eBay: Money Back Guarantee policy, checked Oct 2026.
- Amazon.com: return policy, checked Oct 2026.
- Best Buy US: return and exchange policy, checked Oct 2026.
- Your Europe: guarantees FAQ, checked Oct 2026.
- AOC US and Canada: warranty, checked Oct 2026.
- Dell: Monitor Support Services, checked Oct 2026.
- Tom’s Hardware: simulated 10-year OLED monitor torture tests (27 Sep 2025), checked Oct 2026.
- PC Gamer: Monitors Unboxed two-year OLED test (5 Mar 2026), checked Oct 2026.
- ddcutil: vcpinfo output (VCP code C0, display usage time), checked Oct 2026.
