No POST After Changing AGP Aperture Setting in BIOS

[Zadillo]

Hi all,

I have an MSI K8T Neo2 FISR motherboard, and am using an GeForce 6800GT 256MB video card (AGP)

I have noticed an odd problem. My AGP aperture setting in the BIOS is currently set to 128megs. I was troubleshooting another problem with my system (essentially, every now and then when trying to display a video file in windows, or go to a folder which had videos that it generated thumbnails for, the resolution would get all screwy and the screen would be zoomed into a corner of the screen), and one person mentioned to make sure that the AGP aperture setting was the same as the card's video memory.

I went to the BIOS and changed it to 256 megs, and saved the BIOS, but after doing this, the system won't even POST (the diagnostic LED thing for the MSI K8T indicates it's an error in chipset initialization or something like that). The only way for me to fix it is to use the jumpers to reset the BIOS.

Does anyone have any ideas on what the problem might be? For the most part I haven't had any major problems running it with the AGP aperture settings set to 128megs, but it makes me worried that the system seems to choke when I try to set it to what the card has. Does it mean that it is only using 128 megs if I keep it at that setting, or something else?

-Zadillo

 

[Fern]

Hey Zadillo,

HERE'S an AGP ap Guide. I think after reading it you'll come to same conclusion as I that 128mb is fine given that our cards have 256mb of vram.

No, even if your agp ap setting is at 128mb, your card will still be using all 256mb of it's vram.

Fern

 

[Zadillo]

Cool, thanks Fern. That helps clear things up a lot. One thing that link doesn't address...... it does seem to indicate 128 megs should be fine for the aperture, but it didn't seem to say anything about problems that would be caused by, say, setting a 256 meg aperture on a card with 256 megs of memory. Should I be worried that this seems to cause my system not to POST, or is that fairly normal?

 

[Fern]

Sorry, I'm not sure why that's a problem. The ap setting is for using system ram when your card runs low on vram. Maybe you don't have enough system ram to "donate" 256MB for the aperature. Although my understanding is that the amount specified in the ap setting is not "dedicated" to video use. So prolly s/n matter.

I will say I have seen PCs refuse to handle really low settings too, like 32MB. Maybe it's a BIOS thing?

Anyway, if 128MB works it becomes more of an academic concern and you'll need to find somebody smarter than me to explain it

Anybody else wanna help out here? I'm curious too

Fern

 

[NuroMancer]

First thing to do is a BIOS update.

Fern has most of it right,

You AP setting is not dedicated it just pulls from the system if and when it needs to.

How much RAM do you have installed in the system and what type?

My guess is still that it's a problem with the bios addressing 256 megs of memory in relation to the AP settings. So Update that bios!

First reset the CMOS with the jumpers to get it running.
Bios update
Go to MSI's website and make sure ur drivers are up to date.
Go into bios and try it again.

Oh and 128 shouldn't be the problem. The only other thing I would do is run memtest on the system ram to double check.

let me know

 

[superfly27]

You read different stuff about AGP aperature size every site you go.
For me, I understood 64 MB was a kind of "safe" mode you could use in case you have any problems. But I also read that 128 MB is better or a 64 MB video card. I have a Mad Dog Ti4200 64 MB so I started off with 64 MB and now am at 128 MB. I think gaming etc is better that way (in my case anyway with my Asus A7V600-X).

As far as being able to post is concerned, I was locked out (for whatever reason) out of my own BIOS. I had to unplug my machine, take out the CMOS battery, take out the CLRTC jumper from pins 2/3 and put in on pins 1/2 and three seconds later put it back where it was. Then I had to go in my BIOS and re-do all the settings.

 

[FlyingPenguin]

AGP aperature should be either default (64Mb) or 128Mb (performance gaming but possibly less stable). Any other setting are at your own risk.

 

[Zadillo]

Thanks. I'm pretty sure that I have the latest BIOS installed (MSI's liveupdate program runs about once a week and shows me if there's a newer BIOS version available).

I have 1GB of system memory.

Everything (systemwise at least) seems to be working now after I reset the BIOS (using the jumper on the motherboard).

Thanks for the help!