The Incredibly Simple Question of the Day (AGP)

[Dean Carlson]

Alright, I have an Abit BX6-2 motherboard with a brand new Matrox 6450 on it. Just wondering, under the SoftMenu, the AGP options read as the following:

"AGPCLK/CPUCLK" = 2/3 or 1/1

Current (and default) setting is 2/3 which means, "AGP bus speed will be CPU bus speed divided by 3 and times 2."

Which one is best for the G450? Windows 98se? Etc.?


--Dean
deancarlson@mindspring.com

[Rags]

leave it at default. What it means is what frequency your AGP bus will run at, which is a factor of the front-side-bus speed your motherboard runs at. When it's set to 1/1, that means that the AGP and the front side bus will run at the same speed, 2/3 means that the AGP will run at 2/3rds the FSB. Since AGP is spec'ed to run at 66Mhz, then at FSB speeds of 100 or more, 2/3rds will be default.

Rags

[Kruzin]

It depends on your processor's FSB (Front Side Bus).
If it a P2/P3/P2/Athlon you will be running 100MHz or higher FSB. For this you want you AGP divider at 2/3.
If you are running a 66MHz FSB chip (Celeron,ancient p2) you will want it set to 1/1.
The goal is to run the AGP at it's spec'd 66MHz bus speed.
100MHz FSB * 2/3ratio=66MHz AGP
66MHz FSB * 1/1ratio=66MHz AGP

[Dean Carlson]

Then I assume I want 1/1 since I am running a Celeron 300a right now.

If this makes sense to anyone, the company that pre-tested, pre-made this Celery sandwich had two settings for overclocking, 450 and 464. The 450 list said to keep it at 1/1 while the 464 list said to keep it at 2/3.

I've been at 450 for awhile, but will testing 1/1 or 2/3 do any damage whatsoever no matter what sort of CPU I have?

--Dean
deancarlson@mindspring.com

[Rags]

Well, if you run your celeron at 450, you are running 100 Mhz FSB, you want 2/3 in this situation. Leave the setting at default, and you will be fine. Setting it to 1/1 can damage your video card.

Rags

[Kosh Naranek]

.

[Greebe]

I also would leave it at 2:3 (ie 66mHz) and be done with it.

But...

Setting it to 1:1 could damage it. Not that it definitely will.

It would invariably cause major stability problems unless run at agp1x and even then might not fly straight. At these speeds AGP2/4x do have major stabilty issues and are clearly way beyond the AGP spec.

[Dean Carlson]

Alright, here's another Incredibly Simple Question, then: just where is the settings for AGP1x and above?

There's the 1/1 and 2/3 settings, AGP memory (currently at 64, I believe) -- both in the Abit board's BIOS, but where is the AGP settings?


--Dean
deancarlson@mindspring.com

[Greebe]

What would the point be, it won't improve proformance switching to 1:1 and AGP1x. Actually you will see a slight decrease in proformance.

But if you insist on begging for help without doing any searching on you own, you can grab it here...

ftp://ftp.matrox.com/pub/mga/utils/tech_sup/mtstu414.zip

[Dean Carlson]

Heh, begging indeed.

But I just snagged that program last night -- and to clarify, I don't want to mess with the 1/1 or 2/3 settings, I just think I might want to test out the AGP 1x et al settings since many others in the backlog here have mentioned that making sure it's in 1x helps with stability issues (and even pumping up to 4x gives virtually zero performance increase).

I want to see if the 1x/2x AGP settings affects my monitor problems in any way, shape, or form.

Of course, my new Viewsonic now refuses to turn on, but that's another thread...


--Dean
deancarlson@mindspring.com

[Greebe]

Dean, what I ment was if you had done a search you would have easily found this info and wouldn't have to test it out for yourself. Except the stability issue that is