Analog & DVI

[crb806]

Can someone explain analog and DVI(the sticky just basically said DVI > analog but thats all), this is related to LCD by the way...
very much sppreciated

[Mr.Guvernment]

DVI is a pure digital signal - if your video card has a DVI port and you buy an LCD it is best to use the DVI out to keep it a pure digital signal as opposed to going from VGA (analogue) to DVI as you can lose quality converting from analogue to digital.

[crb806]

i noticed on some LCDs the refresh rate i believe is 60 or 75hz which caps the frames per second for analog? does DVI have some sort of cap?

[tom10167]

Don't even bother with a DVI cable, I have a 19" Samsung and there was ZERO difference between my analog and $40 DVI cable. If someone switched my cable back to analog I'd never know.

[Mr.Guvernment]

i would not say dont bother with DVI - many reviews have show on many LCD"s that a DVI cable can prvetn ghosting and blurring and an over all better picture - if a DVI cable shows NO difference then why make the standard.

this is no diff then people who can run a CRT @ 60mhz, but other need 80mhz or above - to each their own.

[Hamm3r]

I dont see the reason why some high end LCDs still come with analog input. ( like Samsung 915 ) Why make 2 conversions form digital to analog and then back to digital. Makes no sence when even a cheap VGA cards today have DVI output. :confused:

[crb806]

ive seen on a few LCD on analog they only run 60hz refresh rate, which caps frame per sec at 60, if you use DVI will you be able to get more thenn 60 FPS?

[elfiena]

hmmm... this is an interesting point. when lcd response time is at 16ms in general, it is capable of blitting 63 fps in theory. i wonder if the refresh rate will cap at 63 fps with DVI rather than VGA if you set the refresh rate to 65~70 fps on the video card

[tom10167]

i would not say dont bother with DVI - many reviews have show on many LCD"s that a DVI cable can prvetn ghosting and blurring and an over all better picture - if a DVI cable shows NO difference then why make the standard.

this is no diff then people who can run a CRT @ 60mhz, but other need 80mhz or above - to each their own.


Maybe the same reason they ditched ATA for SATA and then now for SATA II?

[crb806]

hmmm... this is an interesting point. when lcd response time is at 16ms in general, it is capable of blitting 63 fps in theory. i wonder if the refresh rate will cap at 63 fps with DVI rather than VGA if you set the refresh rate to 65~70 fps on the video card but in this case i am talking about a LCD where respoonse would be 4-8ms allowing fps to be +100, but analog would cap it at 60 b/c of 60hz refresh rate, so my question is would using DVI lead to a higher frames per second compared to analog granted your video card can perform 100+(hypothetically speaking)

[Mr.Guvernment]

well 4-8ms is not neccesarily that - this is a marketing play - may "12 ms" LCDs are only 12ms from grey to grey and can be 20ms+ from white to black and vice versa..

alwasy research an LCD based on people's experiences as opposed to "beleiving" the "ms" myth.

[crb806]

:eek: :eek: well 4-8ms is not neccesarily that - this is a marketing play - may "12 ms" LCDs are only 12ms from grey to grey and can be 20ms+ from white to black and vice versa..

alwasy research an LCD based on people's experiences as opposed to "beleiving" the "ms" myth.
i know that. its kinda funny on the 8ms i was looking at its black to white as 27ms on average :eek: :eek: :eek:

[Mr.Guvernment]

yuppers!! they can be snealy with that "ms" as i dont think it is regulated too well in terms of what can e submitted for marketing.

[crb806]

im just asking what actually limits the frame per seconds that can be displayed on an LCD given you have a video card that can deliver 100+

[jcw122]

OK first off....who cares if DVI has no visual benefit over analog...its the bling factor of DVI that counts in that case lol

Next, dont worry bout LCD refresh rate...its a "legacy" term and no longer affects modern LCDs. And LCD refresh rate is also not the same as CRT refresh rate.

[crb806]

but im just asking what actually limits the frame per seconds that can be displayed on an LCD given you have a video card that can deliver 100+

[elfiena]

While it is true LCD refresh rate is not the same as CRT, higher fps does make a difference. i remember reading a thread about VR and a lot of interesting information turned up. there's a lag time in the human nervous system that compounds onto the lag of the display which degrades the sense of realism. also, the cross section target of your eyes can distinguish a much much higher frame rate than that of the edge of your view.
speak of DVI... they need to make a KVM with DVI interface instead of VGA D-Connector now lol

[crb806]

but im just asking what actually limits the frame per seconds that can be displayed on an LCD given you have a video card that can deliver 100+ does anyone know is it refreash rate or response time

[Malakai]

I think what the original poster was asking is to explain the difference between VGA and DVI as it applies to an LCD. I will attempt this.

VGA out was created and made for VGA monitors. VGA monitors take an analog input which tells the monitor what to draw on the screen. Since a VGA monitor is an analog device, it takes an analog frequency signal. Your videocard, which does all it's rendering in digital of course, converts its output signal to an analog signal a VGA monitor can understand, and then sends it via the monitors VGA cable to the CRT monitor.

Now, an LCD does not take an analog signal as input, it doesn't understand it. LCD's are purely digital and work with digital signals. When you use your vid cards VGA out for an LCD, the videocard first converts its own natural digital signal to an analog one which a CRT would understand, and then sends it to the LCD. The LCD then recieves the analog signal and coverts it BACK to a digital signal which it can understand. You're doing 2 useless conversions this way, and no analog to digital converter is perfect, so you lose some signal accuracy and picture quality.
Using a digital out (DVI) output on your videocard to the LCD eliminates both the videocard coversions to analog and the LCD conversion back to digital.

So, a simplified signal path for a videocard to an LCD monitor using VGA:

Videocard -> Digital to Analog converter inside video card -> LCD Analog to Digital Converter -> LCD Monitor

Now, for a vid card using DVI:
Videocard -> LCD Monitor

See? Cleaner signal path and fewer conversions = more accurate and clear picture.

Hence, DVI > VGA

[Malakai]

but im just asking what actually limits the frame per seconds that can be displayed on an LCD given you have a video card that can deliver 100+


It takes time for a pixel on an LCD to change color. When you go much over 60fps, the pixels cannot keep up, so you get tearing. There is no actual "refresh rate" on an LCD, just the speed at which pixels can change color. However, the end result is the same as running a game at 100fps on either a 60-75hz CRT or an LCD, you get nasty tearing because the monitor cannot keep up with the changes the vid card is sending it.

[crb806]

Thanks Malakai i dont think it can be said any better, i definitely understand how it works now, but i got 2 more questions lol... if you have 2 video cards (SLi) would you need two DVI connections going into your LCD? and question 2 = what actually limits the frame per seconds that can be displayed on an LCD (if there is one) given you have a video card that can deliver 100+ does anyone know is it refreash rate or response time or something else?
Thanks!

[Malakai]

Thanks Malakai i dont think it can be said any better, i definitely understand how it works now, but i got 2 more questions lol... if you have 2 video cards (SLi) would you need two DVI connections going into your LCD? and question 2 = what actually limits the frame per seconds that can be displayed on an LCD (if there is one) given you have a video card that can deliver 100+ does anyone know is it refreash rate or response time or something else?
Thanks!


Question 1 I cannot answer as I can't come near affording SLI, nor do I think the given performance boost in games is at all worth the increase in cost going from a single card to SLI.

Question 2: In my experience, just turn on vsync and let it cap it at 60fps. In the most subjective of ways, it always seems to look better with it capped at 60fps. On my friends samsung 915n, CSS at 60fps looked 100x better than it looked at 100fps on his 21" sony trinitron.

[ludeboy12]

i got a question about analog vs DVI....

why is it that when i go to watch a vcd or avi or porn or whatever i have to switch imputs on my monitor to analog??

dvi i get sound but the vid is just black......

anyways i always wondered why it does that....