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Mini and monitor refresh rate

J

Jackintosh

macrumors 6502a
Original poster
Mar 21, 2009
573
4
Hi all,

I got a new monitor (Acer x233Hbid) that advertises itself as 1920x1080 with a max refresh rate of 75hz. When connected to the Mini (new 2009) I get 1920x1080 ok, however I only get a 60hz refresh rate. Is there something about the Mini or is it the monitor that limits this to 60hz?

Would I notice any difference between 60hz and 75hz anyway? Since 60hz is unchangeable in System Preferences, I have a feeling that's the preferred setting for LCD monitors.
 
S

shoulin333

macrumors 6502a
Jun 26, 2007
700
21
California
digital (DVI) will only give you 60hz, if you used the monitor in analog (VGA) then you could get the 75hz. But no you wouldn't notice any difference between 60hz and 75hz on an LCD.
 
rogersmj

rogersmj

macrumors 68020
Sep 10, 2006
2,161
1
Indianapolis, IN
The refresh rate is meaningless for LCDs because they don't work the same way CRTs did. I don't know how familiar you are with the way they work, but that 60Hz or 75Hz or whatever meant that's how many times the "ray gun" in the CRT could scan from top to bottom in a second...CRTs drew their image line by line from the top down over a period of time, which is why when you would videotape them you could sometimes see weird scan lines scrolling vertically across monitors -- it was basically the difference between what the CRT was outputting (60 times a second) what what the film (~24 fps or so) was capturing that produced the weird optical effect.

LCD's don't do that line-by-line scanning, they can change the entire screen at once. So the important factor in LCD performance is not refresh rate but the pixel response time, which is a whole 'nother can of worms...but fortunately it doesn't matter much anymore. In the early part of this decade, when LCD's were still kind of new, some of them were extremely slow and prone to ghosting -- up in the 20-30ms black-to-black response time. Now, pretty much everything is down in the sub-10ms range, under which most people's eyes can't detect ghosting.

So...that was my long-winded way of saying don't worry about the refresh rate with your LCD, because it doesn't make a diff ;)
 
J

Jackintosh

macrumors 6502a
Original poster
Mar 21, 2009
573
4
rogersmj said:
The refresh rate is meaningless for LCDs because they don't work the same way CRTs did. I don't know how familiar you are with the way they work, but that 60Hz or 75Hz or whatever meant that's how many times the "ray gun" in the CRT could scan from top to bottom in a second...CRTs drew their image line by line from the top down over a period of time, which is why when you would videotape them you could sometimes see weird scan lines scrolling vertically across monitors -- it was basically the difference between what the CRT was outputting (60 times a second) what what the film (~24 fps or so) was capturing that produced the weird optical effect.

LCD's don't do that line-by-line scanning, they can change the entire screen at once. So the important factor in LCD performance is not refresh rate but the pixel response time, which is a whole 'nother can of worms...but fortunately it doesn't matter much anymore. In the early part of this decade, when LCD's were still kind of new, some of them were extremely slow and prone to ghosting -- up in the 20-30ms black-to-black response time. Now, pretty much everything is down in the sub-10ms range, under which most people's eyes can't detect ghosting.

So...that was my long-winded way of saying don't worry about the refresh rate with your LCD, because it doesn't make a diff ;)
Click to expand...

Great background and info. Thanks much.
 
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