Ask HTG: Diagnosing a Flickering Monitor, Skipping Duplicate Files, and Editing the Hosts File

By Jason Fitzpatrick on December 19th, 2011


Once a week we round up some of the reader questions we’ve answered over the previous week and share them with the greater readership. This week we’re looking at diagnosing flickering monitors, skipping duplicate files while copying, and editing the Hosts file to get rid of annoying software reminders.

Why Is My Monitor Flickering?


Dear How-To Geek,

My computer monitor has started flickering. I’m not sure if it started flickering when I switched to CFL bulbs in my office but that’s the only major change I can think of. Where can I start diagnosing this annoying flicker?

Flickering in Fresno

Dear Flickering,

There are a couple different things you’ll want to look at in order to diagnose. First, if you have an older CRT monitor there are quite a few factors you’ll want to look at. The easiest thing to check is the light bulbs. Remove observe the monitor with the new CFL bulbs off. If there is no flicker without the bulbs then it’s likely you’re computer monitor’s refresh rate is set at or around 60Hz. Fluorescent bulbs, thanks to the 60hz US electric lines operate at, will often flicker, however minutely, at 60hz. If you’re using fluorescent bulbs with a CRT monitor it’s quite possible the flickering of the bulb and the flickering of the monitor’s refresh are working together, as it were. You can either switch to incandescent bulbs (which don’t suffer from electrical flicker) or adjust your monitor’s refresh rate to a higher setting.

If you have an LCD monitor there is no refresh flicker as LCD monitors refresh on a pixel-by-pixel basis and not with the sweep of an electron gun (as CRT monitors do). Again, turn the new light bulbs off and observe the monitor. If the monitor is flickering there are two probable causes. One, you’ve got a bad power supply to the monitor and and it’s causing the CFL bulbs behind the LCD panel to flicker slightly. Two, the power supply is fine but the bulbs are going bad—fluorescent bulbs are notorious for flickering at the end of their life cycle.

Finally if you’ve tested things with the lights off and found no flicker, it’s possible there is nothing wrong with the monitor at all but the issue is entirely with the CFL bulbs. Not everyone is sensitive to the 60hz flicker of fluorescent bulbs but those that are find it nearly impossible to ignore. If you’d like to stick with energy efficient bulbs we’d suggest trying out a different brand. Some brands run at a higher voltage/frequency and the flicker will be less noticeable or gone altogether. Alternatively you could try out LED bulbs which, though currently more expensive, are flicker free.

How can I Copy Files While Skipping Existing Matches?


Dear How-To Geek,

I’d like to easily copy files between directories on my Windows machine but with more features than the default file copier offers. The biggest feature I’d like is the ability to automatically skip duplicate files (to not overwrite files in the receiving directory). What would you suggest?


Copying in Colorado

Dear Copying,

Although the default file copier in Windows has improved a lot over the years, it is still quite bare when it comes to features. We’d suggest checking out previously reviewed SuperCopier to meet your upgraded copying needs. Not only can you set it to automatically skip existing files in the new directory but you can specify other collision settings like renaming the old or new files. SuperCopier also has a host of other great features including the ability to reshuffle the copy queue (if you need a file that’s at the end of the queue to to copy sooner, for example, you can bump it up to the top).

How Can I Edit the Hosts File?

Dear How-To Geek,

I have this program on my computer that constantly phones home and had this annoying reminder system. I called the company to ask if I could disable it and they said there was no toggle in the actual application that could turn the phone-home feature off but that if it really bothered me I could edit the hosts file. The tech support guy essentially said that editing the host file to the company’s update server address to would kill the annoying reminder system. The only problem is that I have no idea what a hosts file is and how to edit it. I’m running Windows 7.


Hosts Confused in Houston

Dear Hosts Confused,

We’re impressed you found a tech support person helpful and open enough to give you useful advice like editing the hosts file to get rid of annoying reminder. The hosts file is a hold over from the early days of the internet and pre-dates the use of centralized DNS servers. Essentially the hosts file is a text document on a computer that helps resolve addresses at the local level instead of at the remote DNS server. You can use the hosts file to override DNS requests. You could, as an example, prank your friends by using the hosts file to redirect to Check out our guide to editing the hosts file here. What you’ll need to do is create an entry in your hosts file that points the address the tech support guy gave you (i.e. to so that when the program goes to call home it just bounces the request off the local computer.

Have a pressing tech question? Shoot us an email at and we’ll do our best to answer it.

Jason Fitzpatrick is a warranty-voiding DIYer who spends his days cracking opening cases and wrestling with code so you don't have to. If it can be modded, optimized, repurposed, or torn apart for fun he's interested (and probably already at the workbench taking it apart). You can follow him on if you'd like.

  • Published 12/19/11
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