Graphics card for UP1500, AGP Compatibility and Signalling Voltages

[Matt Turner]

On Thu, Nov 27, 2008 at 1:26 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Thu, Nov 27, 2008 at 12:22 AM, Matt Turner <mattst88 at gmail.com> wrote:
>> Hi,
>>
>> I'm attempting to determine what graphics cards are compatible with
>> the Samsung UP1500 motherboard.
>>
>> It uses the AMD-761 chipset, which according to both the UP1500 user
>> manual and this Wikipedia article
>> (http://en.wikipedia.org/wiki/Comparison_of_AMD_chipsets) supports AGP
>> 4x.
>>
>> AGP 4x is defined as using 1.5v signalling voltages, whereas older
>> 1x/2x AGP used 3.3v. To prevent you from frying your card, AGP slots
>> are keyed. See http://en.wikipedia.org/wiki/AGP#Compatibility
>>
>> Now, if you look at the picture of a UP1500 motherboard
>> (http://alphalinux.org/wiki/index.php/Image:UP1500.jpg), it clearly
>> has the 3.3v key. This limits the available cards to Radeons through
>> the R300 series. I'd really like an AtomBIOS-enabled R500 to be able
>> to go straight from the blue backgrounded SRM console to a nice kernel
>> modesetting environment, but without the correct AGP keys, this can't
>> happen.
>>
>
> Your best bet is probably a PCI r3xx or r5xx card.  AGP is broken by
> design and it's best to avoid it.  Also, drm kernel modesetting
> support both legacy and atombios based cards, so either will work.

Excellent! I'll have my SRM->KMS after all. :)

Do R300 cards support any kinds of power management? If so, is it
possible that support will be provided in the drivers?

>
>> What's going on? AGP 4x is supported by the board, but not the
>> appropriate signalling voltages?
>>
>
> Even though the chipset supports 4x in theory, the motherboard may
> only support 3.3 volt cards.  Perhaps there were issues with providing
> 1.5 volts to the slot.  It could also be that it's really just a PCI
> slot with an AGP connector.  There are some PPC boards like that.

x86 motherboards with AMD-761 chipsets seem to have universal AGP
slots. In the UP1500's case, it must be a limitation of the board
itself.

Thanks,

Matt Turner