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Comment #1
Just read your AGP SB article - very interesting. I would be interested in the
performance of the AGP w/SB oc'd to 75MHz (Celeron) or 112MHz (PII/PIII). My system runs
very well at 75MHz, AGP x2 w/SB. I'm sure I'm not alone in using this basic setup. Great
articles BTW. Keep up the good work!
Steve Nelson
Thanks Steve,
Unfortunately, most, if not all, AGP cards that support sidebanding will fail when the
AGP bus is trying to run beyond 83MHz. That's why it's not feasible for those who own
cards that support sidebanding to overclock their cards by setting the AGPCLK/CPUCLK ratio
to 1/1, instead of the default 2/3. Wish it could be otherwise but for now, it appears
that we are stuck with sidebanding at a maximum speed of 83MHz.
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #2
I read your guide about AGP optimization and I found it complete and very well done.
Just a question, since I didn't find that explained in your testing methodology: which
way did you enable and disable Sideband on your platform? Is there any flag in the driver
you can trigger through the registry? Do you need some kind of software? Is it just an
option in your motherboard's BIOS?
Please point me out to a solution, since I need to force Sideband "on" in my
platform (an Athlon system with a TNT2 card). PCIList says that Sideband is supported by
the NorthBridge (AMD-751) but not by the card. If I force Sideband "on" on the
chipset side with TweakBIOS the system hangs when loading W98SE. So I'm looking for a way
to enable "SB addressing" on the VGA side. Hope you can help with some hints.
Thanks in advance!
Roberto Buffa
Hello Roberto,
Although it has taken me quite some time to reply your e-mail, I have already acted
upon it and posted a whole pages dealing with how to disable sideband support for your AGP
card.
However, please remember that if your AGP does not support sideband support
out-of-the-box, it's likely that it was not designed to support sidebanding at all. Quite
a few cards are like this because excluding sideband support reduces costs.
Also, enabling sidebanding support while overclocking the AGP bus can hang the system,
particularly if the speed of the AGP bus is high. So, if you want to enable sideband
support, it's best you do it with an unoverclocked AGP bus or one that's only a little
overclocked.
Hope that helps you some! :)
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #3
I have just read your article on AGP Sidebanding Versus AGP Overclocking... It was very
instructive... And I've just some questions about it...
I bought a GeForce card (Creative Labs Annihilator), it is very, very fast, but I'm not
completely satisfied with it... I noticed a lot more of stuttering than with my TNT in
many, many games... Apparently, it seems to be related to the texture transfer. When you
come in a new place with new textures, it seems that you have a small break of some tenth
of seconds or less and this stop is not related to an IO operation on the HD or something
else (no background task, no lack of memory,...)...
I have the same problem with my brother's computer who owns a Guillemot 3D Prophet
(Nvidia Geforce too), and some people complains in the newsgroups that their new Geforce
cards suffer from stuttering (in Flight Simulator 2000, Shadow Man, Unreal Tournament
Demo...) I used a small utility PCIList (from www.entechtaiwan.com)
that tells me that the AGP SideBanding is disabled. Do you think that this problem (the
lack of AGP Sidebanding) is related with the hardware or with the driver ? And do you
think that the stuttering is related with the lack of SBA (clogging the BUS for its
transfer) ?? (For example, I've noticed that I have a lot of slowdowns in the 3DMark99
(First Person Shooter bench)
Thanks you in advance...
Pierre Van Spitael
Hello Pierre,
Unfortunately, I'm not (yet... :)) one of the lucky
owners of a NVIDIA GeForce 256 card so I don't really know what the problem is. But it's
possible that sideband support has been disabled (either temporarily or permanently) to
solve compatibility problems with some motherboards. Remember the problems RIVA TNT cards
had with Super Socket 7 motherboards? Well, they more or less solved the problems by
disabling sideband support or running the cards at AGP1X mode. So, I wouldn't be surprised
if they tried to circumvent any compatibility problems during the initial launch by
disabling sideband support.
I think the disabling of SBA, if that was what it was, was probably done via drivers
because to disable permanently (by manufacturing the cards without SBA), it would mean
that the GeForce 256 cards would be crippled forever by the lack of SBA and they won't be
able to declare that their cards support sidebanding.
If they merely disable it using the current GeForce 256 drivers, that will buy them
time to solve any compatibility problems that may arise though their internal tests while
still allowing them to launch early with less risks of compability issues rising their
ugly heads. If that's true, then it would only be a matter of time before they finally
enable sideband support in their drivers.
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #4
I read your article about disabling AGP sidebanding in order to run at a higher FSB.
Since I had a P-III SL37C that I hadn't been able to get past 527MHz due to AGP problems I
decided to give it a try.
Unfortunately, my TNT doesn't have any options to disable AGP sidebanding. Then I made
a discovery. DirectX 7.0 has a 3rd option under the display drivers section: Disable AGP
support. Well, I decided to give it a try and after a reboot and some messing with my FSB,
I was running stable at 580 mhz running Q3demoTEST. Still no luck at 600, but I'll take
580 for now. Thanks for the help, and I thought you might want to mention this 3rd way to
disable AGP sidebanding in your article.
Nathan
Thanks for that great piece of info there, Nathan! :)
I'll be sure to do an update of this guide just as soon as I download DirectX 7 and try
it out myself.
Thanks again for your help there!
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #5
Hi ,
I just finish to read your article about AGP Sideband and I would like to know
which option must I select for disable the agp sideband in my ASUS control panel of
my ASUS V3800 TNT2.
I must select PCI or PCI with reduced heap? Because I don't want to flash my card
BIOS.
Thanks
PS: I Make a Print Screen for your article
Julien Thery
Hello Julien,
I'm not sure which setting you should choose for your card because I'm not sure what
those settings mean myself. But I'll be contacting ASUS about them and I'll post an update
about it in the guide as soon as I get some news.
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #6
Hi,
Excellent article. It was a very enjoyable and informative read, even for someone very
new to computer hardware.
However, I do have a question/concern. My trusted salesperson at my local computer
store has warned me that overclocking my AGP bus is not recommended as I might damage my
card (G400 Max). I take his warning seriously as he is not against overclocking at all and
has give me several tips on overclocking my CPU. I had my AGP bus running at 83.8MHz
problem-free until his warnings pushed back to the 2/3 multiplier.
Any thoughts on the potential for video card damage from overclocking the AGP Bus.
Thanks again for the article and the BIOS guide!
Naresh Debidin
Policy Analyst
Softwood Lumber Division - EPS
Department of Foreign Affairs & International Trade
(613) 992-6464
Hello Naresh,
Your salesperson is completely correct. It's possible to damage the card while
overclocking the AGP bus. For some unknown reason, I have forgotten to write about it.
Thanks for your reminder. Thanks to it, I have just added a new section that discusses the
problems and danger of overclocking the AGP bus.
Thanks again! :)
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #7
Hi there,
My flat mate and i were having this debate.. neither of us really knew how AGP4X works,
but I said it is probably just AGP2X technology (data on rise and fall) on a new 133MHz
(real) system bus, making an effective 266MHz. He says its another magical
stuff-more-data-into-66MHz mode. Could you please enlighten us?
Ben Just
Hello Ben,
If I'm not mistaken, you are correct. The new AGP4X transfer protocol reduces the
timings of each transfer and thus, further doubles AGP2X's transfer rate.
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #8
Do you have some info on how to disable AGP Sidebanding on a Diamond V770 with the
NVidia ref drivers ? Thanks in advance
Pino Aliberti
Hello Pino,
Nathan (of Comment #4) just mentioned an alternative method
through which sideband support can be disabled. Check it out. All you need is DirectX 7.0.
:)
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #9
Do you think reducing the AGP aperture to 4MB or disabling sidebanding will work with the new
GeForce cards?
Thanks.
Daniel Edgar
Hello Daniel,
Sure, sideband support of the GeForce cards can be disabled, if not via
provisions in the driver then via DirectX 7. But why would you want to
reduce the AGP aperture size to 4MB? There's no performance advantage to
that and most applications require an AGP aperture of at least 8MB in size
to run properly.
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
Comment #10
Hello,
I just read your article re AGP sidebanding. I am wondering, I used to have an Intel i740 video card that
SiSoft Sandra reported as being sideband enabled. Now I have a Creative Labs
TNT2 M64 16MB that is reported as not being sideband enabled. How can I enable sideband addressing? Or if you have any other comments or ideas they would be greatly appreciated.
Thanks,
Tom Bergeron
Hello Tom,
Unfortunately, if your card or its graphics chip was not designed to
support AGP sidebanding, then there's no way you can enable it. The RIVA
TNT2 M64 chip that runs the Creative Labs Graphics Blaster RIVA TNT2 Value
card does not support AGP sidebanding at all. So, I guess enabling AGP
sidebanding for your card is pretty much out of the question since SBA is
physically not present.
Adrian Wong
Adrian's Rojak Pot
http://www.rojakpot.com/
http://www.adriansrojakpot.com/
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