Extra power supply for graphics board

genri wrote:
> i have a pc running with PSU Enermax 400watt +12V1@20A & +12V2@20A.
> I was swapping the old graphics card on mb A7N8X-E Deluxe with a new
> Sapphire Radeon x1550 512mb AGP and i saw the alert on the plastic bag
> to connect this board to the computer's power supply by the provided
> 4-pin molex.
> I did as requested, but i am wondering if there was really necessity for
> the extra power connection as i use the pc only for video&photo editing
> and office work, no 3d games and no overclock.
>
> Thanks for any explanations.
> Genri

Video cards usually have power conversion circuitry. If a connector
is placed on the board, it is probably connected to at least
one of the switching converters. Failure to connect the extra
power connector, could result in no video output.

My AGP card, will actually display a warning on the video screen,
so at least you can tell why the card is not working. But other
cards would give a blank screen, if you failed to connect the power.

Paul
 >> Stay informed about: Extra power supply for graphics board 

On Thu, 14 Feb 2008 17:15:57 +0100, genri <spam RemoveThis @mati.invalid> wrote:

>i have a pc running with PSU Enermax 400watt +12V1@20A & +12V2@20A.
>I was swapping the old graphics card on mb A7N8X-E Deluxe with a new
>Sapphire Radeon x1550 512mb AGP and i saw the alert on the plastic bag
>to connect this board to the computer's power supply by the provided
>4-pin molex.
>I did as requested, but i am wondering if there was really necessity for
>the extra power connection as i use the pc only for video&photo editing
>and office work, no 3d games and no overclock.
>
>Thanks for any explanations.
>Genri

As others have said....

My X1950 Pro 512Meg won't allow the PC to boot without both 4-pins
plugged in....

--
The Zero ST
 >> Stay informed about: Extra power supply for graphics board 

genri ha scritto:
> i have a pc running with PSU Enermax 400watt +12V1@20A & +12V2@20A.
> I was swapping the old graphics card on mb A7N8X-E Deluxe with a new
> Sapphire Radeon x1550 512mb AGP

[snip]

thanks again to all of you for replying....
Saluti from Rome
genri
 >> Stay informed about: Extra power supply for graphics board 

On Feb 14, 11:15 am, genri <s... RemoveThis @mati.invalid> wrote:
> I did as requested, but i am wondering if there was really necessity for
> the extra power connection as i use the pc only for video&photo editing
> and office work, no 3d games and no overclock.

Whereas the resulting failure listed by others is correct, the
reason why is not.

Electricity is not same at both ends of a conductor. That
motherboard has a copper plate for ground completely across the
motherboard. And still, electricity at one end of that copper ground
plate is electrically different from at other end.

How electrically different? Not much if the current flow is small.
But current to the two processors (CPU and video) is both larger AND
changes massively. That massive current change means all ground pins
of other motherboard chips will see different voltages.

We solve this 'sudden demand for current' by doing two things.
First, we put a voltage regulator (power supply) at each processor so
that the adjacent power supply can provide that sudden current.
Second, we route from power supply to those regulators on wires that
bypass all motherboard chips.

Those dedicated cables mean chips on motherboard see little
variation on that copper ground plate embedded in the motherboard.
And it means adjacent regulators can now get more current faster to
the processors.

How much current how fast? Pentiums can demand from less than 1 amp
to tens of amps - in microseconds. Demanding that much more current
that quickly would otherwise upset other semiconductors if powered
from a same motherboard copper plate. Current change so quickly is
the reason for separate connections to the power supply.
 >> Stay informed about: Extra power supply for graphics board 

w_tom ha scritto:
> On Feb 14, 11:15 am, genri <s... DeleteThis @mati.invalid> wrote:
>> I did as requested, but i am wondering if there was really necessity for
>> the extra power connection as i use the pc only for video&photo editing
>> and office work, no 3d games and no overclock.
>
> Whereas the resulting failure listed by others is correct, the
> reason why is not.
>
> Electricity is not same at both ends of a conductor. That
> motherboard has a copper plate for ground completely across the
> motherboard. And still, electricity at one end of that copper ground
> plate is electrically different from at other end.

[
[snip]

> Current change so quickly is the reason for separate connections to the power supply.

hi w_tom, that was a lesson on electricity/electronics i had to go
through your note a couple of times, but i now understand the reason for
the extra power connection on the mentioned video card.
My initial doubt aroused after reading the specs indicated by some
retailers that this new board didn't need external power supply, while
an alert on the plastic container said the contrary.
my cordialities for your views,
genri
 >> Stay informed about: Extra power supply for graphics board 

On Sat, 16 Feb 2008 14:04:44 +0100, genri
<spam.DeleteThis@mati.invalid> wrote:


>hi w_tom, that was a lesson on electricity/electronics i had to go
>through your note a couple of times, but i now understand the reason for
>the extra power connection on the mentioned video card.
>My initial doubt aroused after reading the specs indicated by some
>retailers that this new board didn't need external power supply, while
>an alert on the plastic container said the contrary.
>my cordialities for your views,
>genri


X1550 cards come in both AGP and PCIe interface versions. A
PCIe slot is capable of delivering more current than an AGP
slot can, so in this case it seems an X1550 will have the
external power connector on AGP version but not on PCIe
version. This probably explains the confusion. If a card
has the external connector always use it.
 >> Stay informed about: Extra power supply for graphics board 

On Feb 16, 8:04 am, genri <s....TakeThisOut@mati.invalid> wrote:
> hi w_tom, that was a lesson on electricity/electronics i had to go
> through your note a couple of times, but i now understand the reason for
> the extra power connection on the mentioned video card.

To summarize my post - it discusses 'change of current'. Kony adds
another parameter - constant current number. Every connector contact
(even back in the original ISA) has a max current number.

Another technique used to make 'change of current' a lesser problem:
capacitors are scattered over the motherboard. Another tool in the
art of power distribution. Again, the underlying fact - electricity
is always different at both ends of every conductor. How different? -
is an important parameter.
 >> Stay informed about: Extra power supply for graphics board