VGA cable can make a difference for sure. There can be blurring toward right side of screen, oscillations that cause some bright streaks toward right around text and other fine details, and reflections that cause faint copies of existing details toward right side. Much of it comes from bad impedance matching of the cable but there isn't a good way to test for that other than just trying a cable and seeing how it works. Blurring also comes from excess length, as cable capacitance increases and it will act as a lowpass filter on the high bandwidth signal that is being passed through.

I have found from testing that the cables that come from LCD monitors (at least Samsung ones) are actually often better than many of the thick and fancy looking cables I have. The build quality is actually excellent with foil and braid shielding and importantly (but not always) steel wires with controlled impedance like oscilloscope probe cables, so they have good impedance matching which prevents oscillations and reflections. Any deficiencies really mess up the digitizing process in an LCD monitor so it makes sense these cables are competent.

Usually cheap LCD monitors doesn't seem to have a great quality cable and the one found in shops are usually bad. For a video analog connection looking at the game console experience and on computers at the old add-in video card/decoder cards of the '90s, the cable should be much thicker and each wire should be double shielded from the beginning to the pins end. And such thing would cost A LOT for the manufacturer/user. I tried in the past to make a good cable for game consoles using SCART/RGB connection and passing also audio into it, but the total cost of so many good wires would end up being too high. Also as been said, many "high end" cables sold are not necessary that good once tested while sometimes less known but well built cable result in much better signal. Some high end LCD monitors already had their own cable for this reason imho. I remember an Eizo early LCD monitor having a cable so thick that the cable weight was incredible.

I find most of the time card becomes more of an issue than cable. But I've been trying to find a really short thic cable to test this.

IIRC, VGA does 2048x1536 at 85Hz max. (assuming RAMDACs on your card can actually cope with it).
It doesn't support 2560 horizontal width, so you don't have to worry about signal quality at 2560x1440.
I don't count downsampling/DSR/VSR in above.

PS. Unless you thought 1920x1440 instead of 2560x1440 ?

In my experience, VGA cables are a hit/miss thing when going above 1280x1024. Any cable can fail (thick or thin), so you should get the next one and try again.

In any case, I think that this is pointless... most cards and monitors that can do those resolutions have other means of connection (DVI, HDMI, DP), so I recommend going digital and leave VGA for lower resolutions and/or very old computers.

agent_x007 wrote on 2023-06-03, 10:52:

IIRC, VGA does 2048x1536 at 85Hz max. (assuming RAMDACs on your card can actually cope with it). It doesn't support 2560 horizon […]
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IIRC, VGA does 2048x1536 at 85Hz max. (assuming RAMDACs on your card can actually cope with it).
It doesn't support 2560 horizontal width, so you don't have to worry about signal quality at 2560x1440.
I don't count downsampling/DSR/VSR in above.

PS. Unless you thought 1920x1440 instead of 2560x1440 ?

I just found out about that myself. You are right about that limit. I just had previously read from another web page that the reason why 1440p does not work is because of the signal degradation which now seems to have been wrong information.
I was thinking of getting the native 1440p for a monitor I have but I dont have a dual link dvi cable so I was originally wondering if I could get it from the vga port instead.

VGA has no inherent resolution limit, you can push as high freqs as your video card allows and monitor can accept. The main limit is video card, they usually have 400MHz pixel clock limit on VGA output which makes it impossible to do stuff like 4k for example.

2560 x 1600 @ 60Hz is not at all a problem, it is well below 400Mhz pixel clock limit and Hsync rate is near 100kHz which a normal high end monitor has no issue with.

I attached two images of 2560x1600 that I once experimented with on my 20" Nokia monitor. I didn't expec text to be as readable as it ended up being 🤣

Is it an artificial limitation when a manual of a motherboard for example says that maximum output resolution from d-sub in the I/O panel is 1920x1200@60Hz?

Tiido wrote on 2023-06-03, 13:43:

VGA has no inherent resolution limit, you can push as high freqs as your video card allows and monitor can accept. The main limit is video card, they usually have 400MHz pixel clock limit on VGA output which makes it impossible to do stuff like 4k for example.

2560 x 1600 @ 60Hz is not at all a problem, it is well below 400Mhz pixel clock limit and Hsync rate is near 100kHz which a normal high end monitor has no issue with.

I attached two images of 2560x1600 that I once experimented with on my 20" Nokia monitor. I didn't expec text to be as readable as it ended up being 🤣

To point out few things : You are being very optimistic about what everyone has available to them (OP has modern 1440p monitor, so no CRT magic of not having native resolution for him here).
Connecting VGA output to any modern digital only monitor, will result in reduction of max res/refresh to whatever adapter is cable of outputting (usually 1080p60).

agent_x007 wrote on 2023-06-03, 15:08:

Tiido wrote on 2023-06-03, 13:43:

VGA has no inherent resolution limit, you can push as high freqs as your video card allows and monitor can accept. The main limit is video card, they usually have 400MHz pixel clock limit on VGA output which makes it impossible to do stuff like 4k for example.

2560 x 1600 @ 60Hz is not at all a problem, it is well below 400Mhz pixel clock limit and Hsync rate is near 100kHz which a normal high end monitor has no issue with.

I attached two images of 2560x1600 that I once experimented with on my 20" Nokia monitor. I didn't expec text to be as readable as it ended up being 🤣

To point out few things : You are being very optimistic about what everyone has available to them (OP has modern 1440p monitor, so no CRT magic of not having native resolution for him here).
Connecting VGA output to any modern digital only monitor, will result in reduction of max res/refresh to whatever adapter is cable of outputting (usually 1080p60).

It is 12 years old 1440p 27" ips monitor. I like it because it has VGA input and it also allows you to keep the input aspect ratio as it is unlike some later monitors I have had.

agent_x007 wrote on 2023-06-03, 15:08:

To point out few things : You are being very optimistic about what everyone has available to them (OP has modern 1440p monitor, so no CRT magic of not having native resolution for him here).
Connecting VGA output to any modern digital only monitor, will result in reduction of max res/refresh to whatever adapter is cable of outputting (usually 1080p60).

Optimistic or not, I am talking about the actual physical limits that most video cards with actual VGA output have and which are the primary limitations of what can come out the port. It is inaccurate to say 2048 x 1536 @ 85Hz being the limit. While it does reach 388MHz pixel clock with CVT standard, and could be seen as a higher end due to being near the real limit of 400MHz pixel clock of most video cards and why it is in the VESA standard as the highest thing, and highest you can choose in a typical driver, but in reality, without any optimistic factors, any resolution that fits into the 400MHz limit can be output although one will have to create custom resolutions to do so in many cases. Some drivers allow this to be done without additional tools, many do not and alternative methods are required such as PowerStrip or Modelines etc.
It certainly is true the monitor's own input can be a limiting factor but saying VGA tops out at x resolution, is not accurate. One needs to work down from pixel clock limit of a video card, you take the maximum pixel clock which is usually 400MHz, then divide it with your wanted framerate, line count (including blanking and sync lines) and then you're left with maximum horizontal pixel count that includes blanking and sync pixels. It is as simple as that. Old Radeon 7000 in my test computer has documentation say 300MHz RAMDAC but testing shows it has upper limit of 400MHz as most other things do from that time and beyond.

Baoran wrote on 2023-06-03, 14:30:

Is it an artificial limitation when a manual of a motherboard for example says that maximum output resolution from d-sub in the I/O panel is 1920x1200@60Hz?

This limit can be due to the signal conversion from DVI/HDMI(and sometimes DP) to VGA with some cheap chip, of which almost all have a 165MHz pixel clock limit which is just enough to do this resolution with reduced blanking (which will often not work with a CRT and causes geometry problems at edges of screen) but an LCD that has much smaller blankng needs will be fine with that.
Similarly, using one of the numerous dongles sold on ebay etc. will be similarly limited (since they also use same kind of chips). I am aware of one dongle that actually has max pixel clock specified as 500MHz but it was expensive (couple hundred €) and I don't remember what its name was either but I learned of it from this forum a while ago.
The 165MHz pixel clock limit is something that is relevant for DVI output in particular, it cannot be broken and with DVI to HDMI dongles you are still bound to it. Dual link DVI can double the effective bandwidth though and that 1440p monitor in question absolutely needs such a cable to work at the native resolution. I would expect it to be able to receive its native resolution over VGA too, but only from a real VGA port of a video card and not through a conversion dongle due to previously mentioned aspects.