Question DisplayPort to VGA Cable (PC to Monitor) ..... or..... Must Buy (Active) Adapter ?

worstalentscout

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hi,

i'm using HDMI from PC to Monitor now..............motherboard has DisplayPort and HDMI but no VGA output............monitor has HDMI and VGA......

in case of display problems and i need to find out what is at fault................can i use a DisplayPort to VGA cable (PC to monitor) ..... or..... must i buy (Active) Adapter ?

i've read people using the cable say it works................but others say need ACTIVE adapter............


many thanks in advance............
 

DRagor

Illustrious
DisplayPort to VGA cable
Essentially there is no such thing. DisplayPort uses digital signal, VGA uses analog - so without adapter it simply cannot work. Now, there are adapters sold by the name of 'cable' but they are in fact adapters too - to not search too far let's take a look at this one. Notice how big VGA connector is? That's because it also houses adapter.
i've read people using the cable say it works................but others say need ACTIVE adapter
However it is named, you need quality product. Frankly many of those 'cables' has a lot of bad reviews often along the lines 'worked once then no more'. Active adapters (those that have additional USB plug) seem to be working better. So it is up to you, if you want spend less on a 'cable' and risk high failure rate or spend more on adapter and have working product.
 
Reactions: Lafong
You need an active adapter for the following reasons:
  • DisplayPort does not output a VGA or analog signal (which is what VGA uses) period.
  • The data format DisplayPort uses is not compatible with VGA anyway. DisplayPort sends packets of data, whereas VGA is a constant stream of data
  • The physical signal characteristics are also very much different
Any cable that promises to convert DP to VGA that isn't an active converter is outright lying.
 

worstalentscout

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Essentially there is no such thing. DisplayPort uses digital signal, VGA uses analog - so without adapter it simply cannot work. Now, there are adapters sold by the name of 'cable' but they are in fact adapters too - to not search too far let's take a look at this one. Notice how big VGA connector is? That's because it also houses adapter.

However it is named, you need quality product. Frankly many of those 'cables' has a lot of bad reviews often along the lines 'worked once then no more'. Active adapters (those that have additional USB plug) seem to be working better. So it is up to you, if you want spend less on a 'cable' and risk high failure rate or spend more on adapter and have working product.
the Amazon link you posted is what i'm after...........looks like a cable...........

i actually need to use it to see if it's my motherboard or monitor that's having issues..........

You need an active adapter for the following reasons:
  • DisplayPort does not output a VGA or analog signal (which is what VGA uses) period.
  • The data format DisplayPort uses is not compatible with VGA anyway. DisplayPort sends packets of data, whereas VGA is a constant stream of data
  • The physical signal characteristics are also very much different
Any cable that promises to convert DP to VGA that isn't an active converter is outright lying.
i've read that the ''active'' phrase is wrongly used.............and that all adapters and cables have a chip inside that do the conversion.............

i've seen Youtube videos whereby the DP to VGA cable works...........
 
i've read that the ''active'' phrase is wrongly used.............and that all adapters and cables have a chip inside that do the conversion.............

i've seen Youtube videos whereby the DP to VGA cable works...........
Not all adapters have a chip inside of them. There are DP to DVI adapters that tell the DP port to output DVI instead if the DP port supports "Dual Mode", I don't think these have chips in them.
 

Satan-IR

Distinguished
Ambassador
Yes, as said above, DP to VGA requires converters (not adapters). Basically a DAC (Digitial-to-Analog Converter) chip and circuitry.

As hotaru.hino said, adapters can work on sources with Dual Mode DP support. You need Dual Mode on the source device, or DP++ . This allows DisplayPort sources to use simple passive adapters to connect to HDMI or DVI displays. Almost all devices with DP ports support DP++. Almost.

Devices which have DP++ detect that a DVI or HDMI adapter is attached and send DVI/HDMI signals instead of DisplayPort signals. This is kind of equivalent to singals in HDMI version 1.2, resolution up to 1920 × 1200 at 60 Hz.

There are some limitations too. It's unidirectianl and doesn't work both ways (from native DVI or HDMI source to DisplayPort display too you need an active adapter) and you can only do DVI single-link with passive adapters. Difference in voltage causes slower speeds with passive ones as DP does 3.3V but DVI and HDMI voltage is 5. There's some voltage shifter in the adapter and that causes the speed to drop.

All that said, I too would go for an active adapter from a reputable manufacturer with good reviews to avoid issues later.
 

worstalentscout

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Nov 1, 2016
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Not all adapters have a chip inside of them. There are DP to DVI adapters that tell the DP port to output DVI instead if the DP port supports "Dual Mode", I don't think these have chips in them.
Yes, as said above, DP to VGA requires converters (not adapters). Basically a DAC (Digitial-to-Analog Converter) chip and circuitry.

As hotaru.hino said, adapters can work on sources with Dual Mode DP support. You need Dual Mode on the source device, or DP++ . This allows DisplayPort sources to use simple passive adapters to connect to HDMI or DVI displays. Almost all devices with DP ports support DP++. Almost.

Devices which have DP++ detect that a DVI or HDMI adapter is attached and send DVI/HDMI signals instead of DisplayPort signals. This is kind of equivalent to singals in HDMI version 1.2, resolution up to 1920 × 1200 at 60 Hz.

There are some limitations too. It's unidirectianl and doesn't work both ways (from native DVI or HDMI source to DisplayPort display too you need an active adapter) and you can only do DVI single-link with passive adapters. Difference in voltage causes slower speeds with passive ones as DP does 3.3V but DVI and HDMI voltage is 5. There's some voltage shifter in the adapter and that causes the speed to drop.

All that said, I too would go for an active adapter from a reputable manufacturer with good reviews to avoid issues later.

okay, many thanks for all the detailed info.............. (y)
 

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