I am a little stumped

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OK guys, I am a little stumped on this one.  Recently built a system
for a friend and it works flawlessly in F.E.A.R but will lock up in
Doom 3 and Oblivion among other games.  I have checked all temps and
they are well within normal (CPU is 35C under load, Vid cards are 50C
under load.)

The setup is as follows:
Motherboard Gigabyte GA-8n-SLI-Quad-Royal

2Gig DDR2 667 Running Dual Channel OCZ

2X EVGA PCI-E Video Cards running SLI

2X 250 Seagate HDD Running onboard Raid in striping

P4 3.0 Ghz Cedar Mill Processor

Antec 500W True power PSU

We have tried all of the BIOS revisions available from Gigabytes
We have tried reinstalling Windows and the drivers for all the
I have run memtest on the machine for several hours with no memory
The machine will idle just fine, however whenever in Doom3, Oblivion or
WoW it will randomly lock the sound will loop and it will either
restart itself, or will continue the game just fine.  THe frequency
that it does this seems to be totally random.

Re: I am a little stumped

Cstolworthy@gmail.com wrote:

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I tried downloading the manual, but it didn't help explain things
for me.

You have three major electrical loads and two power connectors.
Your processor uses 12V @ 8A, and the video cards should be around
12V @ 4A each. On an ATX 2.0+ power supply, the processor power
comes from a different output rail, than the video cards.

The processor power should come through the 2x4 power connector.
That should not be a problem. Whether you used a 2x4 connector
or a 2x2 connector, two yellow wires is enough to carry the
needed 8A of current. And the path from the 2x4 connector, to
the Vcore converter is short, so there will be no issues with
motherboard power distribution there.

The video cards do not have PCI Express power connectors. That
means the video cards are drawing their power through the PCI
Express edge card connector. The power could be flowing from
the two 12V pins on the 24 pin main power connector. For your
configuration (and due to the lack of info in the manual),
I would recommend _only_ using a 24 pin power supply with
your configuration. No 20 pin supplies, or 20 pin supplies
fitted with 20 pin to 24 pin converters.

The 8A of current has to flow from the two 12V pins on the 24
pin power connector, all the way over to the faceplate end of
the video card slots. If the motherboard was 6 or 8 layers,
this would be easy to do properly. If the motherboard is
only 4 layer, it is harder to get enough copper in there to
carry the current.

Now, Gigabyte could have done something nasty. They could
have connected the 2x4 processor power connector, to the
video card +12V pins, but that would be lunacy. If they had
done it that way, that should have been documented in the
user manual.

It is for this reason, that when shopping for SLI video cards,
I would recommend finding video cards with PCI Express or
Molex power connectors, to get power for video. It is easier
to make room for the necessary current to flow, via the fat
wires of the power supply cables, rather then through the
thin copper of the motherboard. (On some Asus motherboards,
they solve this problem by placing a Molex power connector
near the video card slots. That gives a shorter path for
video card power to flow, but the method would still not
be my favorite.)

If you had mentioned the exact Antec model of power supply,
that would make it easier to comment on it. I don't think your
overall power consumption is a problem, but I'd still want
to examine the connector types for contributing to your

You can help yourself, by running memtest86+ (boots from floppy
or CD), and by running Prime95 torture test (runs from Windows
or from Linux). Those two tests, if they run clean, will help
eliminate your memory and processor as the source of the
problem. That leaves the video cards as the problem, either
due to driver problems, or due to the limitations of power
distribution. Your power supply probably has enough power,
but if you state the exact model, it'll make it easier to
comment on that - I don't want to guess.


Re: I am a little stumped

Paul wrote:
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The PSU is

Re: I am a little stumped

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The specs are sufficient (19 amps on both 12V1 and 12V2), even if
all the load was placed on one output. So the only remaining issue
I see, is whether the Gigabyte board has paid sufficient attention
to routing the current from the main 24 pin power connector, to
the video card slots.

I presume you've already googled for evidence that the Nvidia
driver code for that new video card, is fault-free.


Re: I am a little stumped

On 5 Jun 2006 08:09:03 -0700, Cstolworthy@gmail.com wrote:


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Try different drivers, especially video and sound.  Try
reinstalling DirectX 9C, even if currently installed just
reinstall anyway.

Try different game settings for video and audio.  What sound
card are you using?  If you're using onboard sound I would
think about getting a Creative labs Hardware EAX sound card
as your P4 3GHz is the weakest link, onboard audio will make
it worse unless you only use 2 channels and no special sound
effects.  You might also disable the sound and see if it
plays ok... only as a test.

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