Black screen at boot time on a Sam460ex - Apple 27 minidp

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Hans
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Re: Black screen at boot time on a Sam460ex - Apple 27 minid

Post by Hans »

@Benny

I already answered in the PM, but for everyone else's benefit...

Actually, before that, please don't send me a PM in addition to making a forum post. It's kind of like sending the same email to all of my email addresses, which is annoying.
Any news on DisplayPort support ?
Sorry, but DisplayPort simply isn't being worked on right now. The main reason is that (almost?) all monitors have DVI/HDMI as well, so it's not something that's essential. There are far higher priority things that need doing. Besides, I don't have a DisplayPort monitor, so I couldn't even test it if I were working on it.
I'm asking this because DVI for my Samsung 4K-monitor, but it only does 30Hz @3840x2160 or does a DVI Duallink cable does 60Hz (?) anyone ?
Short answer, no.

AFAIK, 3840x2160@30Hz has a 297 MHz pixel clock, so 60Hz needs a 594 MHz pixel clock. HDMI v1.2 and below can handle up to 165 MHz per channel, or 330 MHz.

Here's where things get complicated. Southern Islands GPUs have HDMI 1.3, which can handle up to 340 MHz per channel (680 MHz dual-link). It should work with those cards.

NOTE: You'll still need to use dual-link for anything over 165 MHz even with HDMI 1.3 hardware, because the graphics driver currently has no means to detect the presence of an HDMI 1.3 monitor.

Hans
http://hdrlab.org.nz/ - Amiga OS 4 projects, programming articles and more. Home of the RadeonHD driver for Amiga OS 4.x project.

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tonyw
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Re: Black screen at boot time on a Sam460ex - Apple 27 minid

Post by tonyw »

nbache wrote:Seems I've been beaten on resolution ... but not on real size ;-).
Has it come to this? Monitor envy?

Jeez, I remember when 800x600 used to be extreme - you needed those damned 9-pin adapter things..
cheers
tony

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nbache
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Re: Black screen at boot time on a Sam460ex - Apple 27 minid

Post by nbache »

tonyw wrote:
nbache wrote:Seems I've been beaten on resolution ... but not on real size ;-).
Has it come to this? Monitor envy?
Well, let's just say that there are areas where size actually does matter (and increasingly so with age, I might add).

Best regards,

Niels

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Re: Black screen at boot time on a Sam460ex - Apple 27 minid

Post by Benny »

nbache wrote:
Benny wrote:I'm asking this because DVI for my Samsung 4K-monitor, but it only does 30Hz @3840x2160 or does a DVI Duallink cable does 60Hz (?) anyone ?
I am using a DVI-DL cable (and DVI-DL KVM) to display 2560×1600 from my Radeon HD 5450 on my 30" Dell. This is at 50 Hz. But I'm pretty sure you do at least need the DL cable. When I used regular DVI, I could not get more than 1920×1200@50Hz.

P.S. 3840×2160, huh? Seems I've been beaten on resolution ... but not on real size ;-).

Best regards,

Niels
I use a DVI-D (single link) -> HDMI on my Samsung 28d590d to get 3840x2160 @30Hz.
With a Radeon 6450 that is, I adjusted Workbench font sizes to 24 and 32 to make it readable without a loupe.

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Hans
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Re: Black screen at boot time on a Sam460ex - Apple 27 minid

Post by Hans »

Benny wrote:I use a DVI-D (single link) -> HDMI on my Samsung 28d590d to get 3840x2160 @30Hz.
With a Radeon 6450 that is, I adjusted Workbench font sizes to 24 and 32 to make it readable without a loupe.
In that case, you may find that your horizontal resolution is halved (i.e., 1920 instead of 3840), because 3840x2160 @30Hz is definitely over the maximum frequency of a single link.

I have a single-link DVI/HDMI monitor, and I've managed to tip the pixel clock over the limit with 1920x1080 (by plugging in both VGA & DVI simultaneously). The result was every second column of pixels on-screen being missing. So, if you have a single-link cable and attempt to display a resolution requiring a dual-link cable, then you'll still get a displayed image; it will just miss half the pixels (the half that are being transmitted over the second link).

Hans
http://hdrlab.org.nz/ - Amiga OS 4 projects, programming articles and more. Home of the RadeonHD driver for Amiga OS 4.x project.

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