Overclock.net banner

Active vs. Passive Displayport adapters *the truth*

472K views 115 replies 63 participants last post by  TuxKey  
#1 ·
There seems to be a ton of confusion around here about 1) what is required for eyefinity, 2) what an active adapter is, and 3) the difference between active and passive adapters. I am making this thread, hopefully to clear that confusion.

1) Eyefinity requires an ACTIVE adapter to enable a third monitor on HD 5000 cards. Passive will NOT work, except for the first two monitors on the eyefinity 5 and eyefinity 6 cards. For the other three/four monitors, active is still required. A quick explanation of why is because DVI/HDMI requires a special clock, which the card is only able to provide two of. Displayport does not use this clock, so ATI used it as a workaround.

2) An active adapter converts a true displayport signal into DVI/HDMI/VGA/whatever else. It will have either a converter chip or a DAC built in to do said conversion. Contrary to popular belief, they do not need to have a usb power connection, in fact there are many that do not.

3) This is the big one I have been seeing a lot lately. The difference between active and passive is simple.
Passive adapters are merely a cable to go from displayport to DVI/HDMI/VGA/w.e. The video card detects the monitor as such, and outputs the required signal (DVI/HDMI/VGA). This does require one of the two aformentioned clocks, hence why they do not work with eyefinity cards.
Active adapters, on the other hand recieve a displayport signal from the video card, and convert it to DVI/HDMI/VGA. They will always have some sort of onboard DAC or video converter chip which they use to convert the dp signal. Lately, most everyone has been referring the DAC ones (which are the converters that go DP->VGA) as 'passive.' This is not the case.

Examples of passive adapters:

Image


Image


Examples of active adapters:

Image

^ The one most commonly in question. There is also a newer version, which has a cable between the plugs. This is sold under several mfg. names.

Image

^ Sapphire active displayport adapter. There are also similar versions sold by Dell and a few other companies.

Image

^Apple mini displayport -> DVI adapter. I highly recommend avoiding this one, because it seems to only work well with apple monitors.

As far as I have seen, most DP->VGA adapters are active. I say 'most' because, while I have not seen a truly passive one, DP is still capable of outputting the signal, so there is a chance it exists.

Now, go forth and spread the word!
lol j/k. The point of this thread was to a) expose the truth (I go into OCD rage mode when I see people claiming that passive adapters work), and b) protect buyers from buying true passive adapters because they heard the DACs work.
 
#2 ·
so..... how do you explain ALL of the people claiming they got eyefinity to work using a passive DP to VGA adaptor? They are lying perhaps? Can't be 12,600 people all lying just to sell passive DP adaptors can there?

Not jumping on you or anything like that. I'm trying to get an eyefinity setup going myself and the amount of hoops you have to jump through are amazing.
 
#3 ·
Quote:

Originally Posted by foothead View Post
Examples of active adapters:

Image

^ The one most commonly in question. There is also a newer version, which has a cable between the plugs. This is sold under several mfg. names.
Do you have some proof of that? I'm pretty sure its passive. I don't think its possible to produce an active adapter for a tenner.
 
#4 ·
The people claiming they use passive adapters are not truly using passive adapters. They have a DAC in them. It is just misinformation.

I can take mine apart later and post a picture of said DAC if you need.
 
  • Rep+
Reactions: ablearcher
#5 ·
Quote:

Originally Posted by Roxxas049 View Post
so..... how do you explain ALL of the people claiming they got eyefinity to work using a passive DP to VGA adaptor? They are lying perhaps? Can't be 12,600 people all lying just to sell passive DP adaptors can there?

Not jumping on you or anything like that. I'm trying to get an eyefinity setup going myself and the amount of hoops you have to jump through are amazing.

Quote:

Originally Posted by Tehrawk View Post
Do you have some proof of that? I'm pretty sure its passive. I don't think its possible to produce an active adapter for a tenner.

Quote:

Originally Posted by foothead View Post
The people claiming they use passive adapters are not truly using passive adapters. They have a DAC in them. It is just misinformation.

I can take mine apart later and post a picture of said DAC if you need.
Guys...

DP is a digital signal

VGA is an analog signal.

Conversion MUST happen, somewhere.

Just because misinformed, and some dim people, call it a passive adaptor, doesn't mean it is.

It is still actively converting the Digital DP signal, over to an Analog VGA signal.

You cannot passively convert that (not for DP to VGA).
 
#6 ·
Quote:

Originally Posted by ablearcher View Post
Guys...

DP is a digital signal

VGA is an analog signal.

Conversion MUST happen, somewhere.

Just because misinformed, and some dim people, call it a passive adaptor, doesn't mean it is.

It is still actively converting the Digital DP signal, over to an Analog VGA signal.

You cannot passively convert that (not for DP to VGA).

Actually you can, because there is no conversion going on with a passive adapter. Instead, the card outputs the intended signal.
 
  • Rep+
Reactions: ablearcher
#8 ·
Sorry, i do not follow. Do you mean why you could not use tge three together?

VGA needs the same clock as DVI. This would be why.

My point was that the passive converter simply tells the card to output the signal in dvi, vga, or w/e. It still would need the clock, hance why it is not compatible with eyefinity. My point was that, assuming the clock was available, it would be able to output an analog signal.
 
  • Rep+
Reactions: ablearcher
#9 ·
funny the one i have says neather passive or active lol just that its a dp to vga and it works thats all that matters lol

http://www.newegg.com/Product/Produc...82E16812270275

"Model
BrandBYTECC
ModelAP-DPVGA
Spec
TypeDisplayPort to VGA
Features
FeaturesDisplayPort v1.1 Compliant

Enable high quality optional digital audio transmissions

embedded clock architecture to reduce EMI susceptibility

Support greater than QXGA (2048x1536) resolution at 24-bit color depths

Support existing VESA and CEA standards

Support hot plug and unplug detection as well as link status-failure detection

Support reduced bandwidth transmission via direct drive over a 15M cable

Supports a minimum of 1080P resolution at 24bpp, 50/60Hz at 15 M

Support conversion from DisplayPort signal to VGA signal

Support DisplayPort connector 20pins

Support 8-bit & 10-bit deep color

Support the video bandwidth up to 10.8Gbps

Support the 1Mbps' bidirectional auxiliary channel

Support the 1 lane, 1 direction, 4 lines connection"
 
#10 ·
Hi,

I got HD5750, the BYTECC 3 ft Mini DisplayPort Male to DisplayPort Male Video Cable Model DPR-03
http://www.newegg.ca/Product/Product...tent-_-text-_-

connected it to iMAC27".

Does not work: It probably gets the signal, because it goes dark for ~20sec while my PC with the Sapphire flickers during this time. Then everything return back to default.

I contacted the support from Sapphire and they suggest i need an active display port adapter which I can't understand, as all I am doing is sending a signal from displayport (HD5750) to mini displayport (iMAC27).

What do you think and recommend to solve the problem?

Thank you!
 
#11 ·
I have an Early 2009 Mac Mini with Mini DVI and Mini DisplayPort. And I have two 1080p HDTVs. The Mac Mini is capable of dual display, and I've gotten it to work before, so the issue is not the TV or Mac. And I have tried both Mirroring and No Mirroring.

I got a Mini DisplayPort to HDMI Adapter (#5311) and a Mini-DVI to HDMI Adapter (#4852) both from MonoPrice. And for some reason I can't get the Mac Mini to dual display, it's only one or the other.

Before I had a Mini Displayport Male and USB Male AUDIO to HDMI Female Converting Adapter (#5969) and I got video on both HDTVs, but not audio at the same time b/c one was USB and one was TOSLINK.

I'm not sure why I can't get video on both monitors.
 
#12 ·
I too am having the same problem as the user above (apple_pc). I got a Radeon HD5750 and bought a DP to Mini DP Cable (similar model) as above and connected it to the iMAC27". Same problem - it gets its signal and then goes dark for 20 seconds before returning to default. I probably have a passive adapter cable too. But I don't know where to purchase an active adapter DP to mini DP cable. Can anyone assist and does anybody know if this will really work? Thank you!
 
#13 ·
Quote:

Originally Posted by ozzren View Post
I too am having the same problem as the user above (apple_pc). I got a Radeon HD5750 and bought a DP to Mini DP Cable (similar model) as above and connected it to the iMAC27". Same problem - it gets its signal and then goes dark for 20 seconds before returning to default. I probably have a passive adapter cable too. But I don't know where to purchase an active adapter DP to mini DP cable. Can anyone assist and does anybody know if this will really work? Thank you!
make a new thread about this instead of hijacking this one.
 
#14 ·
Hi Guys

Recently got my 3 monitors and have run into some difficulty.

I have two monitors running on DVI and the 3rd is display port to HDMI

When i plug in all 3 i only get signal on the two DVI displays but if i plug in just the display port i get signal... any ideas? Im assuming i have a passive adapter but i had read that you only needed active adapters for monitors that were 30" and up

Any help would be awsome.... but looks like i might need to go buy an active adapter.....
 
#17 ·
hello, hopefully someone could answer, even though this thred is somewhat old
smile.gif

I've been looking at dvi-dp adaptors to get my third monitor to work (all 3 is currently in dvi-dp passive adaptors)... thing is i can find roughly 2 kinds of active adaptors 1 with the extra usb connection at about 90$ and some without the usb at 30$, the cheap ones says that it's active but i'm confused about the price difference! is the normal cheap adaptors that says active on the package enough to get eyefinity to work even though they do not have external power?
 
#18 ·
Quote:
Originally Posted by Panickypress View Post

hello, hopefully someone could answer, even though this thred is somewhat old
smile.gif

I've been looking at dvi-dp adaptors to get my third monitor to work (all 3 is currently in dvi-dp passive adaptors)... thing is i can find roughly 2 kinds of active adaptors 1 with the extra usb connection at about 90$ and some without the usb at 30$, the cheap ones says that it's active but i'm confused about the price difference! is the normal cheap adaptors that says active on the package enough to get eyefinity to work even though they do not have external power?
I'm just about to test a 5 display system with the cheaper non-usb adapters. I'll report my findings.
 
#19 ·
I know there are other threads that cover this, but it seems like clear answers haven't exactly been given regarding the latest adapters...

If the adapter is not specifically labeled as Active, and it does not have an extra USB cable to provide power, the odds are it is passive. I tried a generic one like this when I couldn't find something specifically labelled as active at my local shops. What you will see is that your CCC shows three monitors connected, but you can only run 2 at a time. It will be impossible to setup a three monitor eyefinity group.

When you have an actual active adapter, you will see three monitors in CCC again, but you can actually expand your desktop or clone to all three at the same time, no issues. You will also be able to setup an eyefinity group as well with no issues.

The cheapest ACTIVE adapter I found locally was the XFX one. No USB needed, just a display port, short cable (4" or so) and DVI port. Max res is 1900x1200 with this type. If you need a higher res, you will need one of the expensive usb powered active adapters. Example usage would be for running dual-link DVI monitors like 30" 2560x1600 beasts... If you can afford multiple ones of those, you can afford the better adapter. :)

NewEgg has a few to choose from in the $25 - $39 range. Saphire has some without USB now, as well as some other off-brand companies. Even more helpful, some are actually stating on their packaging if they are eyefinity compatible. In most cases, they appear to be correct. :)

Anyway, my testing was done with 5870's going to DVI only monitors. I'm about to test one more variable when I hook up my 5970 in eyefinity mode. I need a mini-displayport to regular displayport, then my active dp adapter to go to my DVI connection. Wish me luck... ;)

Have fun!
 
#21 ·
Thank you +rep. Answered the questions I had about DP adapters.
 
#22 ·
Damn who really cares it was a damn good thread that explains alot for everyone. To trully make this thread worth wild, this thing should be "sticky" with updated links to the the best working/cheapest adapters that will get the job done. Put out the top 5 best adapters that we need to get eyefinity up and rolling with AMD/ATI cards so we don't have to search for stuff we don't know about. One stop shop
biggrin.gif
Lets get them links rolling!!! I got three Catleaps that are waiting for me to purchase and i don't know which adapters to get.
 
#23 ·
Hello,
This is a great thread....

the OP had a great explanation, and I haven't had the time to verify it fully but it makes sense.

In a nutshell the away these display ports work seems is that :

1st that graphic card starts talking to the connected monitor, and it then discovers if the connected port is analog or digital, and what the specifications of the monitor are. If the monitor is accepting digital data (often don't) then the card has to transform that digital data directly, otherwise it has to convert it into a power hungry analog format.

For all those electrical engineers out there (like me) , the reality is that both signals are digitally coded, but the "older" technology (VGA DVI HDMI) has a higher current deliverance and a less sensitive receiver... think of it as LVDS. On the other hand Display Port has a smaller current deliverance and therefore needs to be talking to a smart and sensitive receiver.. think of it as Current Mode Logic (CML)...

Another big deference is that VGA is feed forward only, so the graphic card never hears back from the monitor in VGA mode. Display Port talks to the monitor and retrieves information back from it... this information could be resolution and refresh rate and also coded digital information to improve the signal integrate of the link.

So some cards actually are capable to deliver the data in an analog format from all 3 ports, because they have the power, actually all ports have the amplifier to deliver in VGA format... its just that if you connect all 3 in that format you get less power delivered to each driver, and higher chance of getting bad data received at the input... This is called Bit Error Rate (BER), and honestly,,, companies do like to sell you a $100 converter.

I have a 6 display 5870, and have had a hard time getting all 6 of them to work, even tho I have 4 active converters and 2 passive converters .... I could get 3 working with passive converters although it says that I need 1 active and 2 passive in the website. If my theory is right, then having 5 or 6 active converts should get my 6 displays working with no pain... right now it is very painful... as screens go blank and resolutions get missed up...

Hope my 2 cents helps someone out there... please correct me if I posted anything wrong... I'll report back when I get my 5th active converter and try it out.
 
#24 ·
Everything that the OP said is true

I had to find out the hard way, wasted like $300 on adapters & extensions that people claimed it works with Eyefinity, but they did not.
mad.gif
way back in March 2012 when i picked up my 2x 7970 DC2 TOP

In the end had to pick up 6 Accell Active Adapters, and all problems were gone
thumb.gif


shall have i went that route from the beginning and i would have saved myself $300 for another type of upgrade, a new cell phone or more HDD space perhaps
tongue.gif
 
#25 ·
#26 ·
I had 3 Saphire dp-dvi adapters witch did not work with 3 displays, then changed 1 of them to a HIS active adapter and all works perfect.. This adapter was just as cheap as the passive, with no external power. If you have a mini dp i do not know, but for 3x dp you do no not need separate power, just 2x dp-dvi + 1x active dp-dvi adapter... even the cheap ones!