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-   -   Gainward GeForce4 Ti 4200 and overclocked AGP (http://www.nvnews.net/vbulletin/showthread.php?t=1876)

Prefect47 09-15-02 05:14 PM

Gainward 4200 128Mb and OC AGP?
 
Just got a Gainward Ultra/650XP (4200 with 128Mb) and I can't get it to do what my several-years-old Matrox Marvel G200 card did for a long time: run in a system with 133MHz fsb and a 2/3 AGP multiplier.

System:
Abit BX6 v2.0 mobo
PIII 933MHz (locked at 7x)
SB AWE32 (ISA) sound card
Intel EtherExpress Pro100 (or something like that)
256MB 133MHz mem
2 HDs - I think one is 7200rpm, not sure though.
DVD-ROM and CDRW (i.e. two drives)
300W PSU (due to earlier power problems)

I run XP, and the system loads to the point right after it switches to the desktop resolution where you log in, then I get a black screen with a white pixel in the top left corner (probably the mouse pointer) and everything stops cold. Bumping the fsb to 124MHz makes it all work, but it means that the cpu is underclocked and that's what I'd like to avoid.

Help? I've searched the forums but haven't found similar issues (doesn't mean there aren't any, so feel free to point me to threads). BTW, I couldn't search very much for this particular issue, since such strange and unfamiliar terms as "agp", "fsb", "89 mhz" are less than 4 characters long... :)

Have tried booting XP into VGA mode, but as soon as I increase the resolution to 1024x768x32 the system hangs.
Have tried the latest (40.x) nVidia drivers, no difference.

Gator 09-16-02 07:54 AM

sorry to ask a really naive question, it's been awhile since I worked on a 440bx board with anthing higher than a 100fsb. But is there a reason you can't use the AGP 1/1 setting?

Prefect47 09-16-02 08:10 AM

Doesn't the 1/1 setting stress the AGP port even more (or have I horribly misunderstood that setting)?

I thought that multiplier was how the AGP frequency was derived from the fsb?

Gator 09-16-02 08:18 AM

http://www.rojakpot.com/Speed_Demonz...CLK_CPUCLK.htm

AGPCLK/CPUCLK
Common Options : 1/1, 2/3, 1/2

Details

The AGP bus clock speed is referenced from the CPU bus clock speed. However, the AGP bus was only designed to run at 66MHz while the CPU bus runs anywhere from 66MHz to 133MHz (266MHz when clock doubled). Therefore, a suitable AGP bus to CPU bus clock speed ratio must be selected to ensure that the AGP bus won't run way beyond 66MHz.

When the ratio is set to 1/1, the AGP bus will run at the same speed as the CPU bus. This is used for processors that use the 66MHz bus speed, like the older Celerons.

The 2/3 ratio is used when you use a processor running with a bus speed of 100MHz. The ratio will cut the AGP bus speed down to 66MHz.

The 1/2 ratio was recently introduced with motherboards that provide 133MHz bus speed support. Such motherboards need the 1/2 AGP bus to CPU bus clock speed ratio to make the AGP bus run at the standard 66MHz. Otherwise, it would have to run at the overclocked speed of 89MHz, which is more than what most AGP cards can withstand.

Generally, you should set this function according to the CPU bus speed you are using. This means the ratios of 1/1 for 66MHz bus speed CPUs, 2/3 for 100MHz bus speed CPUs and 1/2 for 133MHz CPUs.

If you are overclocking the CPU bus, theoretically you are supposed to reduce the ratio to ensure that the AGP bus speed remains within specifications. However, most AGP cards can run with the AGP bus overclocked to 75MHz. Some even run well at 83MHz! However, anything above 83MHz would be a little iffy.

Thus, in most cases, when you overclock the CPU bus, you can still stick with the original AGP bus to CPU bus clock speed ratio. This means that the AGP bus will be overclocked as well. But as long as the AGP card can stand the higher clock speed, it shouldn't be a problem. In fact, you can expect better AGP bus performance when the AGP bus is overclocked.

Be warned though - overclocking the AGP bus can potentially damage your AGP card. So, be circumspect when you overclock the AGP bus. 75MHz is normally the safe limit for most AGP cards.

Prefect47 09-16-02 08:53 AM

So the 1/1 setting would mean, in my case, running the AGP bus in 133MHz. I still don't understand why that would be better than running it in 89MHz.

Someone told me this problem could be caused by the drivers, too... and he recommended that I installed the 28.x drivers, and do it manually. Can that help?

sbp 09-16-02 03:34 PM

Quote:

Originally posted by Prefect47
So the 1/1 setting would mean, in my case, running the AGP bus in 133MHz. I still don't understand why that would be better than running it in 89MHz.
1/1 setting would not be better. Stick with 2/3-even then the AGP bus is running out of spec big time.

Quote:

Someone told me this problem could be caused by the drivers, too... and he recommended that I installed the 28.x drivers, and do it manually. Can that help?
It might. Try it and see.

Prefect47 09-16-02 03:50 PM

Success!

The 28.32 drivers from Gainward, installed manually (i.e. not through their own little program) did the trick. Now running 133MHz fsb, 89MHz AGP, with 260MHz Core Clock and 520MHz Memory Clock :D

Will run like this for a few days, test a few games, the usual. The only downside is that I can't get the improved performance of later drivers...


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