[alligator]

I have a Mac Pro connected to an Apple 23" Cinema display. This is the best display that I've ever owned.

I have a Sony Vaio PC that I'd also like to connect to this display, but it only has a VGA connector. If I use a VGA KVM switch (since DVI KVM switches are so darned expensive - $50 vs. $225) will I see a substantial reduction in display quality with my Mac Pro?

I don't want to do this if the display will look horrible.

Also, my PC can't fill the 23" display. What will happen - will there just be black bars on the edges?

[mduell]

Any KVM that can take a VGA input from your Sony and output DVI to your Cinema Display is going to be over $300.

Also, many LCDs over VGA look like ****. But if you want a bigger screen for your laptop, drop $100-200 on a 19-20" VGA LCD.

[ghporter]

A 23" ACD has a really BIG resolution, right - 1920 X 1200? VGA needs a lot of VRAM, and a lot of bandwidth to support such resolutions. While a DVI-VGA converter might technically allow you to drive that display with your Mac, even a high end Vaio WILL have problems giving you a decent display, simply because of the huge data requirements for such a high-resolution screen.

mduell's observation about many LCDs looking bad with VGA is valid; a decent LCD will look at least OK with at least a VGA signal, but VGA-specific LCDs don't handle higher resolutions as well as they handle VGA resolutions. The flip side is that an LCD that's built to handle DVI (which is the crux of mduell's statement) WILL look like poo with even a decent VGA signal; few VGA cards have enough bandwidth, VRAM, and speed to properly drive such "eye candy" displays. I have two Dell 17" VGA-specific LCDs, and they look great-driven by VGA inputs. They'd probably look pretty good with a DVI input through the DVI-VGA adapter that came with my MacBook Pro. But I'm not going to go out of my way to find out, because the display on my MBP is fantastic.

[mduell]

Originally Posted by ghporter 

A 23" ACD has a really BIG resolution, right - 1920 X 1200? VGA needs a lot of VRAM, and a lot of bandwidth to support such resolutions. While a DVI-VGA converter might technically allow you to drive that display with your Mac, even a high end Vaio WILL have problems giving you a decent display, simply because of the huge data requirements for such a high-resolution screen.

mduell's observation about many LCDs looking bad with VGA is valid; a decent LCD will look at least OK with at least a VGA signal, but VGA-specific LCDs don't handle higher resolutions as well as they handle VGA resolutions. The flip side is that an LCD that's built to handle DVI (which is the crux of mduell's statement) WILL look like poo with even a decent VGA signal; few VGA cards have enough bandwidth, VRAM, and speed to properly drive such "eye candy" displays. I have two Dell 17" VGA-specific LCDs, and they look great-driven by VGA inputs. They'd probably look pretty good with a DVI input through the DVI-VGA adapter that came with my MacBook Pro. But I'm not going to go out of my way to find out, because the display on my MBP is fantastic.

ghporter, I think you're going a bit overboard about the needs of the 23/24" LCDs.

VGA was running CRTs at 2048x1536 for years before the 1920x1200 LCDs were on the market, so the bandwidth is there. The vast majority of PC OEMs are still shipping VGA on the majority of their laptops, even with the high end GPU/VRAM systems; DVI has not caught on. And when you're running Windows rather than OSX, the GPU/VRAM requirement for 1920x1200 drops dramatically (GMA900/950 with 64-128MB will be fine). Any VAIO should be fine with any VGA display when running Windows.

I agree, the Dell E-series LCDs (which only have VGA inputs) are the only LCDs that I've seen that look decent with a VGA input.

[Peter]

a 1920x1200 will easily be powered by VGA.

[ghporter]

Originally Posted by mduell 

ghporter, I think you're going a bit overboard about the needs of the 23/24" LCDs.

I simply wanted to emphasize that a monitor built for DVI inputs is going to "need" more and faster data input than most VGA cards, particularly laptop VGA cards, can provide. Of course I have been known to get carried away with "what's proper" and what's not for certain hardware.

Originally Posted by mduell 

I agree, the Dell E-series LCDs (which only have VGA inputs) are the only LCDs that I've seen that look decent with a VGA input.

Those are pretty darn nice displays-Samsung OEMs I think, which says good things about Samsung.

Originally Posted by Peter 

a 1920x1200 will easily be powered by VGA.

Sure, but not necessarily by a Vaio's VGA card-which may have only as little as 64MB of VRAM, and may also have a limited repertoire of resolution modes. 1920x1200 isn't what I'd call "common" in the Windows world. Again, I got carried away with getting across the idea that driving a huge monitor (at least by resolution) with an itty-bitty video card is just not the best idea.

[mduell]

Originally Posted by ghporter 

Sure, but not necessarily by a Vaio's VGA card-which may have only as little as 64MB of VRAM, and may also have a limited repertoire of resolution modes. 1920x1200 isn't what I'd call "common" in the Windows world. Again, I got carried away with getting across the idea that driving a huge monitor (at least by resolution) with an itty-bitty video card is just not the best idea.

Again, this is Windows, not OSX. Assuming he's not thinking of playing games, it puts very little strain on the graphics card.
VGA is just the display connector; it has zilch to do with the performance of the graphics card.

[mhuie]

Originally Posted by ghporter 

A 23" ACD has a really BIG resolution, right - 1920 X 1200? VGA needs a lot of VRAM, and a lot of bandwidth to support such resolutions. While a DVI-VGA converter might technically allow you to drive that display with your Mac, even a high end Vaio WILL have problems giving you a decent display, simply because of the huge data requirements for such a high-resolution screen.

mduell's observation about many LCDs looking bad with VGA is valid; a decent LCD will look at least OK with at least a VGA signal, but VGA-specific LCDs don't handle higher resolutions as well as they handle VGA resolutions. The flip side is that an LCD that's built to handle DVI (which is the crux of mduell's statement) WILL look like poo with even a decent VGA signal; few VGA cards have enough bandwidth, VRAM, and speed to properly drive such "eye candy" displays. I have two Dell 17" VGA-specific LCDs, and they look great-driven by VGA inputs. They'd probably look pretty good with a DVI input through the DVI-VGA adapter that came with my MacBook Pro. But I'm not going to go out of my way to find out, because the display on my MBP is fantastic.

I think you're talking out your ass with the requirements here.

1900x1200 requires a whopping 8MB of VRAM, I wouldn't call that a LOT.

I run dual monitor 21" samsung lcd and dell 24" lcd (1900x1200 and 1600x1200) on an old Matrox dualhead card with 16MB VRAM. Crystal clear.

[ghporter]

Originally Posted by mhuie 

I think you're talking out your ass with the requirements here.

1900x1200 requires a whopping 8MB of VRAM, I wouldn't call that a LOT.

I run dual monitor 21" samsung lcd and dell 24" lcd (1900x1200 and 1600x1200) on an old Matrox dualhead card with 16MB VRAM. Crystal clear.

Thanks for the sterling vote of confidence. I don't think anyone would be interested in a 1900X1200 display that was driven by only 8MB of VRAM; the details, color and most important the motion of such a display would be very disappointing. I was (as I pointed out in my above reply to mduell) I was talking about a dynamic, highly detailed display.

Originally Posted by mduell

Again, this is Windows, not OSX. Assuming he's not thinking of playing games, it puts very little strain on the graphics card.
VGA is just the display connector; it has zilch to do with the performance of the graphics card.

I was indeed thinking about game graphics in this case, or at least high-level graphics like what I'd want to have for video effects and editing (the VAIO's forte, supposedly). For plain-Jane surfing, word processing and such, you can get away with a lot less. Not 8MB, for crying out loud-how many colors can you get with 8MB at 1900X1200? Three? (That was sarcasm-it looks like you get a pretty high color range with 8MB of VRAM, but how about video paging, predrawn frames, and prerendered surface effects? It takes a lot of VRAM to handle more than just the basics of text output.)

And the VGA connection has a lot to do with it: it only has a 3 different (analog) color data lines when compared to DVI, a fully digital, high-bandwidth (SIX high data rate digital channels!) connection. That translates to an ability to pass far more data far faster, which means less ghosting and fewer artifacts on the same resolution screen. For fairly static images, like text and web pages, this is not an issue, but what about movies and games?

The less-than-stellar AGP card in my PC desktop maxes out at 1280X1024 and has 64MB of VRAM. It's not the world's best video card by any means, and while it's fine at driving a 17" VGA LCD display, I'd certainly want something with more bandwidth (for that all-important motion and frame rate factor) to drive a DVI-native display. I see this as like driving a HUGE widescreen TV with a bad VHS tape player-it'll work, but will you be really happy with the results?

[mduell]

Originally Posted by ghporter 

And the VGA connection has a lot to do with it: it only has a 3 different (analog) color data lines when compared to DVI, a fully digital, high-bandwidth (SIX high data rate digital channels!) connection. That translates to an ability to pass far more data far faster, which means less ghosting and fewer artifacts on the same resolution screen. For fairly static images, like text and web pages, this is not an issue, but what about movies and games?

The less-than-stellar AGP card in my PC desktop maxes out at 1280X1024 and has 64MB of VRAM. It's not the world's best video card by any means, and while it's fine at driving a 17" VGA LCD display, I'd certainly want something with more bandwidth (for that all-important motion and frame rate factor) to drive a DVI-native display. I see this as like driving a HUGE widescreen TV with a bad VHS tape player-it'll work, but will you be really happy with the results?

I believe the VGA connector can support 1920x1200 at 32bpp at 60Hz (I've seen 1600x1200x32x75 on CRTs, and the math works out about the same), which is the max input specs for the 23" display.
Ghosting is due to the type and specification of the liquid crystal, not the connection.
Your analogy is totally fallacious, since the graphics card can provide a full resolution signal without upsampling, as the VCR would.