View Full Version : Bios & memory problems

Peter M
13-10-2002, 01:56 PM
I ran Aida 32 system tool on my setup and it came up with the following two problems.
1 AGP aperture size is more than half of the system memory size.
What does this mean and how do I correct it?

2 System bios is more than 2 years old. Update if necessary.

I have a Pentium 2 300Mhz 64Mb ram 4.5Gb hard drive running Win 98

Graham L
13-10-2002, 02:17 PM
If your computer works, you can solve these problems by not running Aida 32. :D

If it's a bit slow, look for memory specials, and add some. 64MB is probably a bit low for Windows, these days.

The AGP message tells you that video can use lots of system memory (if you use graphics heavy applications ... like games).

A BIOS upgrade is needed if something does not work, and it is known that a BIOS upgrade will fix it. If it's not broken, don't fix it.

Terry Porritt
13-10-2002, 02:24 PM
AGP aperure size is set in the CMOS (BIOS) setup, and is an amount of memory allocated from your 64MB ram that could be taken up and used by your AGP video card.
You can try experimenting a bit, but with your system then maybe 16MB would be appropriate.

As regards BIOS update, if all is working well, it is best to leave alone, as BIOS flashing can be a bit dangerous if things go wrong.

If you have a m/b manual have a look at the BIOS section and see what the options are for AGP aperture settings, often 64MB in later systems is the default.

To get into the CMOS setup (incidently not really the same as the BIOS, though the 2 are used interchangeably, BIOS code can only be changed with a special program, CMOS setup is a user changeable thing)
you usually press the DEL key as the comp is booting, there may be a message at the bottom of the screen, but different brands have different ways to get into the setup, eg Compaq use F10.

Terry Porritt
13-10-2002, 02:26 PM
Graham is always first :)

Peter M
13-10-2002, 06:44 PM
Thanks for the reply. I will leave it alone while it is going ok.

Susan B
13-10-2002, 07:54 PM
It's well worth adding some more ram to a system like yours. I've got a PII 266 that had 32MB ram and I added an extra 128MB last year. The difference in speed was amazing and stopped me craving a new PC for a bit longer.

Other people on the forum with much faster machines upped their ram too and also noticed a big improvement. It's worth doing. :-)

13-10-2002, 08:24 PM
I have a 266 P2 and I used to have 64M. Since I added another 128M my machine has been a lot more responsive - particularly with big Java apps like JBuilder.

I tried to get a new BIOS for my machine so I could install a 500MHz P3, but when I attempted to flash the new one I downloaded from the Internet it said "WARNING: Different Part number" even though I'm almost certain it was in fact the right one. In any case I was too scared to go ahead, and ended up taking the P3 back to the shop I bought it from. If you muck up the BIOS it could be VERY hard to restore your PC.


14-10-2002, 11:13 PM
As most others have already said, it's not a good idea upgrading your BIOS unless there is a reason to (upgrading to a later CPU etc) and it would seem you don't have one. AGP apeture size refers to how much system memory, over and above dedicated video memory, can be made available for graphics usage if your graphics sub-system needs it. A lot of CMOS settings for your era machine default to 64MB, I would suggest setting it to 32Mb if you play a few graphics-intensive games or 16MB if you don't.

What motherboard are you using?

Oh yeah, and more RAM is definitely a good idea for your machine.

15-10-2002, 11:57 AM
"AGP Aperture Size (MB)
Options : 4, 8, 16, 32, 64, 128, 256
This option selects the size of the AGP aperture. The aperture is a portion of the PCI memory address range dedicated as graphics memory address space. Host cycles that hit the aperture range are forwarded to the AGP without need for translation. This size also determines the maximum amount of system RAM that can be allocated to the graphics card for texture storage.
AGP Aperture size is set by the formula : maximum usable AGP memory size x 2 plus 12MB. That means that usable AGP memory size is less than half of the AGP aperture size. That's because the system needs AGP memory (uncached) plus an equal amount of write combined memory area and an additional 12MB for virtual addressing. This is address space, not physical memory used. The physical memory is allocated and released as needed only when Direct3D makes a "create non-local surface" call.
Win95 (with VGARTD.VXD) and Win98 use a "waterfall effect". Surfaces are created first in local memory. When that memory is full, surface creation spills over into AGP memory and then system memory. So, memory usage is automatically optimized for each application. AGP and system memory are not used unless absolutely necessary.
Many people recommend the AGP aperture size should be half of the amount of RAM you have. However, that's wrong for the same reason why swapfile size shouldn't be 1/4 of the amount of RAM you have in your system. As with the swapfile's size, the AGP aperture size required will be smaller as the graphics card's memory increases in size. That's because most of the textures will be stored on the graphics card itself. So, graphics cards with 32MB of RAM or more will require a smaller AGP aperture than graphics cards with less RAM.
If your graphics card has very little graphics memory, then you should set as large an AGP aperture as you can, up to half the system RAM. For cards with more graphics memory, you shouldn't set the aperture size to half the system RAM. Note that the size of the aperture does not correspond to performance so increasing it to gargantuan proportions will not improve performance.
Still, it's recommended that you keep the AGP aperture around 64MB to 128MB in size. Now, why is such a large aperture size recommended despite the fact that most graphics cards now come with large amounts of RAM? Shouldn't we just set it to the absolute minimum to save system RAM?
Well, many graphics card require at least a 16MB AGP aperture size to work properly. This is probably because the virtual addressing space is already 12MB in size! In addition, many software require minimum AGP aperture size requirements which are mostly unspecified. Some games even use so much textures that AGP memory is needed even with graphics cards with quite a lot of graphics memory (32MB)."

from "The BIOS Optimization Guide rev. 6.2" by "Adrian Wong"

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