Weird DirectX 7 / AGP Fast Writes Problem

[Wayne Bradney]

[Cross-posted here in case any of you guys can help]

Well, not really a problem since I've not much use for DirectX7 these
days, but it's bugging the hell out of me all the same.

I have two practically identical PCs:

Both Shuttle XPC SB51G w/ FB51 V1.3 motherboards
Same BIOS FB51S035, all settings are identical (trust me)
Both ATI Radeon 9600 Pro AGP (ATI branded)
One has 2.66GHz P4 (we'll call this PC1), the other 2.53GHz P4 (PC2)
Both 512MB Memory (same brand, purchased together)
Both run Windows XP Pro
Both have ATI Catalyst 3.6 drivers and control panel

Seriously, the only thing different about these two machines is that
one is black and one is silver, and they have different types of HD,
floppy, CDROM.

Now, when I run dxdiag on PC2, all DirectDraw and Direct3d test are
fine, and "AGP Texture Acceleration" is Enabled. On PC1, the DirectX 7
Direct3d test produces the spinning cube, but the logo is garbled. The
test completes OK otherwise. All other tests are fine, but "AGP
Texture Acceleration" is "Not available".

In the ATI control panel, with default settings, there are some
differences:

In Options->Details:
PC2: Current Bus Setting = AGP 4X
PC1: Current Bus Setting = 0

In SmartGart:
PC2: FastWrite = On
PC1: FastWrite = Off

If I turn on FastWrite on PC1, it seems to allow it, reboots but then
still shows "Off".

It's the DirectX 7 test (garbled logo) that's bugging me the most,
along with why the hell two identical setups yield different options.
Is SmartGart disabling FastWrites because the processor is slightly
faster on PC1? Is it FastWrites = Off that is making "AGP Texture
Acceleration" unavailable? Is the availability of AGP Texture
Acceleration affecting my DirectX 7 test? I've read elsewhere that the
AGP Texture Acceleration option relies on some BIOS flag. I can't find
such a flag in either BIOS, and if it were there it would be set the
same way in both cases.

I've also switched the video cards - the problem follows the
motherboard, not the card, so I can rule out the Radeons as the
problem.

I don't really see any performance differences between the two (yet -
but I haven't tried many games so far), so I'm not all that concerned,
but when I see two identical machines yield different configuration
options, I get this urge to want to explain it. Can anyone help?

See here for a screenshot of the DX7 test. The cube spins, but the
surface is garbage:
http://www.bradney.com/~wayne/dx7fail.jpg

 

[Ar Q]

Did you check both PCs have the same BIOS setting?

 

[NT Canuck]

I don't really see any performance differences between the two (yet -
but I haven't tried many games so far), so I'm not all that concerned,
but when I see two identical machines yield different configuration
options, I get this urge to want to explain it. Can anyone help?

Make sure that in the control panel system/hardware/device manager/
system devices.... that the processor to AGP device is present...
if not, you need to update the mainboard *.inf and drivers or the
mainboard chip drivers. Then install dx9.0b (current) and set any
display/advanced/troubleshooting... sliders to full accelleration.

reboot and try again...(bios should be PnP OS installed and the
AGP aperture equal to the video card ram...in my experience).

<The Radeon 9600 is a DirectX 9 video card>

 

[Wayne Bradney]

Genius. That did it...

I don't see any "processor to AGP" device or similar in the Device
Manager, but I did take your advice and re-install the mainboard
drivers, DirectX 9.0b, and Catalyst 3.6 + Control Panel again (in that
order), and now dxiag shows AGP Texture Accel = Enabled and the
control panel options are identical on both machines. And, of course
the DirectX7 test now looks fine. There's no real-world performance
benefit, I know, but it's been bugging me all the same.

Thanks for the lead,
WMB