| Date: | June 25, 2004 / year-entry #252 |
| Tags: | tipssupport |
| Orig Link: | https://blogs.msdn.microsoft.com/oldnewthing/20040625-00/?p=38713 |
| Comments: | 46 |
| Summary: | Some people are more sensitive to lower monitor refresh rates than others. Go to the display control panel and click to the Settings tab. From there, click the Advanced button and go to the Monitor tab. From there, you can adjust your screen refresh rate. As a rule of thumb, higher refresh rates are less... |
Some people are more sensitive to lower monitor refresh rates than others. Go to the display control panel and click to the Settings tab. From there, click the Advanced button and go to the Monitor tab. From there, you can adjust your screen refresh rate. As a rule of thumb, higher refresh rates are less likely to cause eyestrain. If you pick a refresh rate and your monitor goes all blooey, don't panic. Just wait fifteen seconds and the system will switch back to the original settings. (If you have a Plug and Play monitor, it's supposed to report the refresh rates it supports, but sometimes that doesn't work.) Note that not all refresh rates are available at all screen resolutions, so if you want to crank the rate higher, you may have to sacrifice resolution. |
Comments (46)
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This really only applies to CRT monitors. Although Windows gives LCD monitors a refresh rate, the value doesn’t really mean much.
I used to work with a guy in PSS who stalked around the office looking for monitors with low refresh rates, and forcibly resetting them. I think he was particularly sensitive about it, but fair enough – people who work in that area should know better. His name was TristanK and he knew his stuff.
I find it truly amazing how many people don’t ever realize their monitors hurt their eyes and give them headaches due to low refresh frequency. Most people make a surprised face when they I tell them their monitor flickers ("Where? It does?"). I have very sensitive eyes and by looking at a screen (well, more like looking down or sideways) I can easily tell if its refresh rate is below 85Hz.
Also, I find it very perplexing that in Linux there’s no easy way to set a refresh rate like it’s done in Windows. I lost count of how many times I screwed up my xf86 settings to the point that it would blow up after a startx command. All I wanted was a refresh rate close to 85Hz.
Of course, ever since I started using a laptop for daily work I haven’t had this problem. Still… I think people need to be educated about it.
No, I just knew what I liked – and I hate 60hz refresh rates. Especially at the corner of my eye… I still do that today, FYI. As soon as anyone new starts, I’m around there to say "Hi", and fix their )*%% refresh rate.
Make sure you activate ClearType as well if you are running Windows XP, it makes a huge difference.
http://www.microsoft.com/typography/cleartype/tuner/1.htm
I don’t notice right away if I am looking directly at the monitor, but if I look out of the corner of one eye, a screen with a refresh of 60hz is crazy.
I can see it flicker and jump all over the place. It can be odd, stop by someones desk to talk to them and then get distracted by the crazy "flickering" going on…"Do you have sore eyes? No, why? Because you have a really low refresh rate."
I can also spot them flickering if I am at least 20 feet away.
That ClearType tuner is awesome. I did the Snoppy Dance when I found that thing. It really needs to be included in the OS though.
Another point beyond refresh rate is to make sure you get your eyes checked regularly. At least once a year, twice if you can swing it. Even with a high refresh rate or a good LCD, staring all day at a point eighteen inches infront of you is bad news.
Milan Negovan: When I first started using Linux in 1997 there was a configuration program for XFree86 called, I think, xf86setup. It would let you pick your monitor from a (limited) list or type in the frequency ranges specified in the manual. I imagine most distributions still have tools like this. You can tweak the settings later with xvidtune. XFree86 version 4 supports DDC (plug-and-play for monitors) so it usually picks the highest possible refresh rate just like Windows does.
If it goes all wonky because you picked an unsupported refresh rate you can hit escape instead of waiting 15s.
During that 15s Windows is displaying a "Do you want to keep this setting?" dialog. If you hit esc, that is the same as saying ‘No’.
-jmd
I always thought the flickering was actually caused by the closeness of frequency to AC power, and thus the "refresh rate" of lighting. I was under the impression that essentially our eyes adjust for the main lighting source and have to strain to also keep up with the second source at a close frequency but out of sync.
This makes me wonder some things that perhaps somebody out there will try. If the monitor was outside (or under natural lighting only) would the flickering be noticeable at 60Hz? I believe EU power is at a different frequency, would they have a different "evil" frequency? And lastly, as refresh rates increase, as you approach 120Hz (a factor of 60Hz) will this become an issue again.
My pet peeve has all but disappeared – old VGA monitors emit a loud whine somewhere on the 15k-20kHz range, especially as they age. Most people can’t hear it, but it drives me crazy!
Incandescent/halogen lights glow because they are very hot. Their light output doesn’t turn on and off at 60Hz. iirc, flourescent tubes run at a much higher frequency.
Televisions run at a far lower refresh rate, but people rarely complain about them flickering. The phosphors stay on longer after the electron beam sweeps by ’em. I can only guess that monitors have shorter persistance because it was annoying when things blurred together.
Warning: If you increase your CRT’s refresh so much that it gets close to its physical bandwidth limit (a.k.a. maximum pixel clock, typically measured in MHz), the image will get blurry. The blurriness is especially noticeable at higher resolutions, but it will affect your eyes to some extent regardless of what resolution you’re using. And as if that weren’t bad enough, it will significantly decrease the life of the CRT as well.
Because of this, as a general rule of thumb, it’s safest to keep your vertical refresh rate at least 5Hz below the highest setting the OS offers for any given mode. For example, if you’re running at 1024×768, and Windows offers up to 95Hz for that mode, pick something like 85Hz. Your eyes — and your wallet — will thank you.
There are times when I need to use of my 19" CRTs to do application testing at pretty high resolutions. Although the monitor can do 2048×1536 at 70Hz, it’s just too blurry to be used for very long like that. I’ve found that 2048×1536 at 60Hz, despite the nasty flicker, is actually more tolerable.
When I need to run at 2048×1536 for more than just a few minutes, I use a third-party utility called PowerStrip to set it up at 2048×1536 at 65Hz. It’s a nice compromise between the blurriness and the flicker.
Don’t forget the Advanced button on the Settings tab. Click that, go to the Adapter tab, and click List All Modes. All your resolutions/color depths/refresh rates in one list. Bam!
AndrewSeven:
Human eyes are more sensitive to color in the center of our vision, and to luminance in the periphery. Since flicker is a change in brightness (luminance), a monitor that seems okay when you look directly at it will flicker when seen on the edge of your vision. This is also why, in low light levels, you "see something out of the corner of your eye", but then don’t see anything when you turn to look at it.
Don Newman:
The flicker you see in monitors iS not a beat frequency between the AC lighting and the monitor. it’s just that human eyes tend to see flicker until you get up to around 70 hertz. Some people see flicker at lower, and some at higher frequencies.
Flicker would be noticeable outside in the sun as well as inside. The problem is that you would have to wait until sunset (or get up early) because sunlight so overpowers a monitor’s brightness, that just seeing the image is hard enough.
Josh:
Fluorescent tubes turn on and off at 120 Hz. AC power is a sine wave that goes both positive and negative. Thus, for 60 cycles of AC, you get 60 positive "peaks" and 60 negative "troughs", resulting in 120 transitions from zero volts to full power.
A bit of trivia: motion pictures are shot at 24 FPS. Given that, you would expect massive amounts of flicker when seeing a movie. Why don’t you? Because motion picture projectors use a rotating disc as the shutter, and the disc has two slots cut into it. This means that every frame of film has two pulses of light sent through it before a new frame is pulled into place. But at 48 Hz, doesn’t that mean it should still be flicker central? Well, it is. But since we’re staring at the big screen with the middle of our vision, it tends not to bug us as that much. Also, the flicker is most noticeable if there is no film in the gate, but that’s not something most people ever see.
"Test this mode" was how Windows NT originally did it. Fifteen seconds was introduced in Windows 95.
I don’t know what is up with my eyes but if I view a CRT at 60Hz then my eyes start hurting after a few seconds and start tearing up a little after that.
In Europe the legal minimum for health and safety is 72Hz (based on some study done years ago). In the US I find people with low refresh rates all the time.
I can just about tolerate 75Hz (depends on the colour etc), and am fine at 85Hz which is what all my personal monitors are set to.
At one point my eyes went hyper sensitive and I could see TV flickering (this was in Britain hence PAL at 50Hz). For about a month I couldn’t watch TV for more than a few minutes. The syndrome mysteriously disappeared.
Raymond,
Do you know where the ‘optimal’ setting disappeared to in Windows XP? It is rather annoying to switch video modes and have it select 60 Hz when the monitor can do over 100 Hz. Any games that do not specifically set the refresh rate when changing modes will cause it to select 60 Hz. I know that some graphics cards drivers can force a certain rate to be retained upon mode switching, but this used to be available from within Windows.
I don’t think you’re supposed to do that for LCD displays. For those, you’re supposed to set the refresh to 60hz I believe.
Jason: There are some utilities that can force a specific refresh rate for both the Desktop and full-screen apps/games. I’m using RefreshLock, which seems quite good.
Milan:
Recent versions of XFree86 or the X.Org server have the XRandR extension, which allows changing the resolution and refresh rate.
Recent versions of KDE (IIRC from 3.2 up) have a Control Center module which uses it to allow you to change it as easily as you would do on MS Windows (at least Windows 98 or 2000 — I don’t know if something has changed on newer versions).
Josh, if you put a monitor outdoors, then the picture will be overwhelmed by the bright ambient light (unless the sun is down).
Your eye percieves flicker more easily in peripheral vision. That’s why *TristanK’s neighbors’* monitors bother him when they are not set right. Central vision is different.
Interlaced TV’s don’t have dramatically lower refresh rates than 60Hz. They refresh at about 59.99…Hz. The complication is that that is the field rate. They do a full picture at 29.99…Hz. The interlacing causes some flickering artifacts, but these normally occupy just a small area of the screen.
Cooney: no kidding! And the high-pitched whine often gets worse if people turn off their computer, but leave the monitor off. I spend many an early evening in the office walking around turning people’s monitors off so I can work in peace.
As for 60Hz, even if you have fluorescent lights, these do have some sort of flicker. What makes the monitor flickering *worse* is having the refresh rate very, very close to the AC switching rate. Kind of like when you look at a fan: at certain speeds the blades seem to be standing still.
I have some problem with the ~90Hz frequencies for the same reason (it’s not a multiple of 60, but they have a high common factor). I actually prefer 72 — or sometimes 84.
Raymond: did Win95 actually restore monitor settings after 15 seconds? I recall some old versions of Windows just switching them with no recourse… but there was usually a "test this mode" button.
Elias Fotinis: Thanks for the tip. I am actually using RefreshLock, as well. I notice it has some bugs, though:
All of a sudden the application I am developing returned a failure for the BilBlt() function. I checked into it and I ensured that all parameters are correct at the time the error occurs. It seems as though you can get RefreshLock to modify the resolution without Windows ‘realizing’ it, and if a 3D screen saver kicks in and then stops, Windows returns the screen to the resolution it THOUGHT it was in (not the resolution you instructed RefreshLock to change into). This causes a momentary failure of all BitBlt() calls. I have even noticed some dialog boxes, which handle redrawing themselves, fail (i.e. some of the buttons do not appear, but they still ‘work’).
In any case, it is a neat program, and seems to work 99.9% of the time, but it would be nicer if I did not have to run yet another application in the background to handle something Windows *used* to handle.
I can only assume that the ‘optimal’ option was removed due to some graphics drivers reporting incorrect refresh rates, thus causing problems. It sounds like another one of those things that everyone blames Microsoft for, yet, you find out they have a totally valid reason for remove the feature. Is this true, Raymond?
If you do have a low refresh rate you can’t change, filling the screen with darker colors will help. The old white on blue routine from the DOS days. Not all programs respect every change you make to the window color settings.
A note of caution: apparently a refresh rate of 100hz interferes with reading.
J. Edward Sanchez: The blurriness at high resolutions you sometimes get could also be to do with your graphics card.
IIRC, a while back there was a problem with various el-cheapo brand nVidia graphics cards having less-than-desirable analogue output quality at higher resolutions (usually above 1280×1024). I remember reading a page that described a process to modify the board to get a better signal. Had a look for it, but could only find this copy of a Google-cached page:
http://www.maxuk.net/241mp/geforce-image-quality.html
Slightly OT, but…
For an interesting experiment, look at a monitor (or TV) and chew on something cruncy (like chips or a dry cookie). You’ll see an interference pattern. I think the chewing sets up vibrations in your skull, which vibrates your retinas.
Is it true that you shouldn’t change the default 60Hz refresh rate for LCD’s? Can someone give me a definitive answer on this please, mine is set to 75Hz which it can support, but I don’t want to find out that I am damaging it in any way.
Thanks.
True, But what if I cant change my refresh rate since It doesnt have any choices in the drop-down menu?
CF: My LCD supports 60-75Hz as well. If you connect it to a 85Hz signal, it will show "out of range". So, I think it’s idiot-proof enough to not show modes it cannot support. Since it does show 75, I guess it’s safe.
Also, you get the picture refreshed 75 times a second as opposed to 60, which would make for smoother display (mouse pointer movement).
Cooney: Me too! PAL TVs emit this 15KHz sound too (25Hz * 625 scanlines = 15625Hz). My own 21" TV has it fairly low, but my mom’s new 29" it really terrible – I can hear it from outside the house. If I buy a new TV, it’ll have to be a "100Hz" set, or I’ll be constantly bothered by this.
Thanks Jonathan, but am I not right in thinking that LCD’s are not affected by ‘flicker’ – and there for smoothe or unsmoothe displays? That was why I was wondering if it mattered whether or not you changed it?
Also, I assume that there isn’t much difference in choosing the Standard PnP driver (which it ran on for some time) or the standard "Digital Flat Panel" driver? I only ask as the manufacturer doesn’t supply any custom driver.
Actually, forget the second paragraph, the manufacturer has recently released drivers.
when will you notice an improvement over your headaches.
I just upgraded from win98 to win2000 professional and just experienced a headache. (I also have one eye – blind in the other)
I changed the refresh rate to the highest one about a half an hour ago but still feel pressure in my head.
I turned the brightness down on my monitor as well.
Is this all because I upgraded?
Can someone give me answers to the following questions regarding LCD monitors please?
1) Is it true that refresh rate is irrelevant on LCDs? When I change mine from 60Hz to the manufacturers stated maximum the horizontal lines between the rows of LCDs become more prominent – and on some games, faint diagonal lines can be seen scanning down the screen. Has this caused any lasting damage?
2) Am I right in thinking that since I am using a LCD display, diffrent refresh rates can have no effect on the ‘fuzziness’ of, for example, text? If it does have an effect, could this be the reason why I am able to see the horizontal lines of LCDs (question 1) more clearly at higher refresh rates?
3) Does is matter that the driver for my SiS graphics will not allow me to select "LCD" for my display? Will the fact that I can only select "CRT" have any effect on the image?
4) There is an effect I’ve noticed on monitors, a kind of "chromatic graininess" that becomes more prominent if you move your head from side to side in relation to the monitor. This was more pronounced on my old CRT, but I can see it to a lesser degree on the new LCD. Is this normal? Is it affected by refresh rate, or am I only imagining that it has become worse after I started to alter the refresh rate to the monitor’s maximum?
Any response welcomed, thanks.
i have flickering with my monitor when my refresh rate is below 60 and i change it to
85 and my screen resolution is 1024 7658
i feel not good to look with the monitor
look to monitor giving me hedache
give me a reply
I have 2 new 19" CRT’s. My video card is 32MB matrox millenium dual head (old motherboard only support AGP 2). When I sent the refresh rate at anything ABOVE 60, the screens flicker. Why is this? The displays do not look bad at the 60 hz, which is weird as at home I run at 85.
Note: I used to have a 64mb card in the machine with 1 montor. Same problem.
Could it be the curren/power of the office?
I’M looking to purchase a 19" lcd. The one I like is a Princeton #lcd19d. It has a contrast ratio of 700:1 it has analog & digital interface & a responce time of 25ms. Best of all it’s only $559 at Cosco. But here’s my question. Most 19" lcd’s have a refresh rate of 75hz this one has 60hz. Should this keep me away from this monitor or doesn’t make that much of a difference?
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http://weblogs.asp.net/oldnewthing/archive/2004/02/21/77681.aspx
PingBack from http://www.quickonlinetips.com/archives/2005/03/change-refresh-rate-of-your-monitor-avoid-flickers-and-headaches/
Raymond Chen recently had an interesting blog post on the importance on checking your monitor's refresh