Incorrect AGP bus speed?!

Hello guys,
just recently I started having problem on my overclocked system. While on Windows (XP) desktop, with black colour background, I noticed different colours of square dots, appearing randomly. If I refresh the desktop (F5), they would all be cleaned out. The problem becomes more noticable while playing games. In 3D games, it's often that the graphics would just flickering and sometimes the graphics messed up completely where random weird textures appearing everywhere on the screen. When it gets worse, the whole system would run slower and slower (with graphics intesive program - 3d games). I know it sounds like video card's memory problem at the start, but I am pretty sure it's not, as I have tested my video card on my friend's PC and it ran without a glitch. While I put his video card on my computer, same problems.
Then, I suspected it's something to do with AGP bus speed. When I use SiSoft Sandra, this bit of Motherboard Information was produced:

AGP Bus
Version: 1.00
Speed: 100 MHz
Current Data Trasnfer Rate: 2x 100MHz (200MHz data rate)
Side Band Enabled: No
Side Band Support: Yes
Fast-Writes Enabled: No
Aperture Size: 128MB

PCI Bus(es)
Version: 2.10
No Buses: 1
No Bridges: 33MHz
Mutiplier: 1/3x

Does that mean my AGP bus is running at 100MHz speed? If so, why does it do that? Shouldn't the motherboard automatically adjust it to 2/3 (my motherboard doesn't have option to change AGP divisor)? Something looks weird there I thought...could there be other things causing weird graphical problem?

Any help would be very much appreciated. Thanks.

J.B.
========================
AOpen AX6BC Pro, lastest BIOS.
Celeron 600@929, 103MHz, 1.9V. Leadtek GeForce 2 GTS.
1X 128 PC100 SDRAM
1X 256 PC133 SDRAM
Creative Soundblaster Live! Value
etc.....

JBatOC said:

Hello guys,
just recently I started having problem on my overclocked system. While on Windows (XP) desktop, with black colour background, I noticed different colours of square dots, appearing randomly. If I refresh the desktop (F5), they would all be cleaned out. The problem becomes more noticable while playing games. In 3D games, it's often that the graphics would just flickering and sometimes the graphics messed up completely where random weird textures appearing everywhere on the screen. When it gets worse, the whole system would run slower and slower (with graphics intesive program - 3d games). I know it sounds like video card's memory problem at the start, but I am pretty sure it's not, as I have tested my video card on my friend's PC and it ran without a glitch. While I put his video card on my computer, same problems.
Then, I suspected it's something to do with AGP bus speed. When I use SiSoft Sandra, this bit of Motherboard Information was produced:

AGP Bus
Version: 1.00
Speed: 100 MHz
Current Data Trasnfer Rate: 2x 100MHz (200MHz data rate)
Side Band Enabled: No
Side Band Support: Yes
Fast-Writes Enabled: No
Aperture Size: 128MB

PCI Bus(es)
Version: 2.10
No Buses: 1
No Bridges: 33MHz
Mutiplier: 1/3x

Does that mean my AGP bus is running at 100MHz speed? If so, what does it do that? Shouldn't the motherboard automatically adjust it to 2/3 (my motherboard doesn't have option to change AGP divisor)? Something looks weird there I thought...could there be other things causing weird graphical problem?

Any help would be very much appreciated. Thanks.

J.B.
========================
AOpen AX6BC Pro, lastest BIOS.
Celeron 600@929, 103MHz, 1.9V. Leadtek GeForce 2 GTS.
1X 128 PC100 SDRAM
1X 256 PC133 SDRAM
Creative Soundblaster Live! Value
etc.....

Click to expand...

1:
Do you have the card overclocked, or are you running any 3rd party overclocking / enhancing utilities, or even coolbits?
2:
If the card ran fine in a friends computer, I would definately lean towards a driver / software issue.
3:
After I was sure there was in no way a driver / software issue I would start looking to the BIOS settings. You may even want to try "Load default setups" in the BIOS just to ensure that isn't the problem.

Report back after you go through these things, and we'll take it from there.
I hope I've been able to help a little, let me know how it turns out!
Joey

Re: Re: Incorrect AGP bus speed?!

killem1x1 said:

1:
Do you have the card overclocked, or are you running any 3rd party overclocking / enhancing utilities, or even coolbits?
2:
If the card ran fine in a friends computer, I would definately lean towards a driver / software issue.
3:
After I was sure there was in no way a driver / software issue I would start looking to the BIOS settings. You may even want to try "Load default setups" in the BIOS just to ensure that isn't the problem.

Report back after you go through these things, and we'll take it from there.
I hope I've been able to help a little, let me know how it turns out!
Joey

Click to expand...

First of all, thanks Joey, for your prompt reply, appreciate it.

Now, to answer your questions:
1. No, video card is running at its default core/memory speed. It was installed with a fresh Windows XP, a NVidia driver was applied immediately after that.

2. Both my and my friend are using the same Nvidia reference driver (23.11). We both also use Windows XP.

3. At this moment, I have set it back default CPU clock (66MHz X 9) and done serveral testings with 3d games and other things, the problem seems to be gone. In SiSoft Sandra, now AGP Bus' Current Data Transfer Rate is at 2 x 67MHz (134MHz data rate).

With my experience, I have a feeling its got something to do with abnormal AGP bus speed. Unless Sandra's reading is wrong, it seems AGP bus is running exactly as the speed as whatever the FBS is set to. It gets me very worry, 100 MHz might just have damaged the motherboard's AGP slot.

J.B.

I think your motherboard just doesnt support 2/3 agp division. my bh6 does, however and it has that option in the bios. you might want to run your fsb at 83MHz or less to keep the agp speed lower. what cpu do you have?

Overclocker550 said:

I think your motherboard just doesnt support 2/3 agp division. my bh6 does, however and it has that option in the bios. you might want to run your fsb at 83MHz or less to keep the agp speed lower. what cpu do you have?

Click to expand...

Hi Overclocker550,
the CPU is Celeron II 600 that can be overclocked to 929 (103 MHz). There is a bit part of story that I did not tell. Originally, I was using Abit BH6 v.1.0 (lastest BIOS) with the same other hardware components. It was when the problems I described above became so serious and I was simply not able to fix it by changing BIOS setting, reinstalling softwares etc, so I decided to replace the motherboard. Yes, then the problem's gone for a while....but now it's coming back

That's how I get very confused now. I feel it's got something to do with the AGP bus speed, but on BH6, it's got divisor (I always have it set at 2/3), so that didn't look like to be the cause. What else could it be?

J.B.

thats weird. the bh6 can actually support celermines with the latest bios flash? wow....mine has the latest bios flash, but abit's website says it only supports up to 450MHz p2. not that it matters since im getting a new motherboard or two or three
maybe the problem is your motherboard fails to automatically switch to 2/3 agp. you might as well run it at say 90MHz fsb for now. you wont notice much of a speed loss

AGP bus speed is now corrected...

Good news, now APG bus speed is correctly running at 2/3 of FSB. It turned out to be the Slot1 to Socket370 converter (SOLTEK SL-02A++) that caused motherboard's AGP bus speed divisor not working at the way it should be. If the converter is set (through jumpers) to detect CPU frequency automatically, MB's AGP speed will run at the same speed as what the FSB is set to, 2/3 divisor will not work. When manually setting jumpers on the converter to run FSB at 100MHz, the MB will then have correct AGP divisor, 2/3. Start from there, I was then able to clock FSB slightly higher to 103MHz, from MB's BIOS and yes, 2/3 divisor is still there. With a successful reboot, checking with SiSoft Sandra, it now says:

AGP Bus
Version: 1.00
Speed: 69 MHz ---> 103 X 2/3, correct!
Current Data Trasnfer Rate: 2x 69MHz (138MHz data rate)
Side Band Enabled: No
Side Band Support: Yes
Fast-Writes Enabled: No
Aperture Size: 128MB

PCI Bus(es)
Version: 2.10
No Buses: 1
No Bridges: 34MHz
Mutiplier: 1/3x
-------------------------------------------

Hopefully, that'd be the fix for graphics disaster I have encountered. One more week of testing is needed.

Now, this makes me wondering, if that long running at high AGP speed (103MHz for more than 6 months!!) has permanently damaged that Abit BH6 board, or just temporarily.....

J.B.