AGP Aperture Size

[lePobz]

Probably the biggest misconception amongst gamers and random PC geeks is that the 'AGP Aperture Size' in BIOS is where you tell your system how much video memory your graphics card has - and that if you only set 64mb in BIOS where as your Video card has 128mb, then only 64mb will be used.

This is wrong.

The BIOS AGP Aperture Size setting is used to determine how much of your systems RAM should be used as dedicated video memory when the Video cards onboard memory overflows.

The best setting would be to set this at half of your total RAM (eg. 256mb for systems with 512mb memory) - or if you have over a gig, just set it as high as it will go.

Now you know (if you didn't before) :cheers:

 

[sharp]

yeah... that question is already explained in the bios and the mobo manual!

at least my mobo :cheers:

 

[FictiousWill]

That doesn't help me get dxdiag to recognize agp on my radeon 9800 pro.

oh well.

 

[manny_c44]

Whats the point of having 256MB cards then? Is it significantly slower going through your regular ram?

 

[lePobz]

Yeah, and it's not like your 'regular ram' is always empty, that's where the game itself is... and if that runs out of space, it would have to start loading the ram content into the pagefile, and that's when the system would really bottleneck.

 

[manny_c44]

But isn't regular ram faster than the videocard's ram? Ignoring the fact that it isn't actually attached to the card? Lets say you had a gig of PC 4200 or whatever RAM, would it be a viable alternative to GPU ram?

 

[lePobz]

Some memory chipsets do use shared ram as they have no video ram of their own (notable in most notebook laptops) - it is a viable alternative, but not for extreme graphics chipsets... for the graphics speeds we all know and love, the video chipset needs very high-speed memory (much faster than regular memory) as close to the GPU (graphics processing unit) as possible.

 

[The Terminator]

will it improve performance at all?

 

[lePobz]

will what improve performance at all?

If you mean sorting out your AGP aperture size in bios, yeah it will, under some circumstances, like if your video card only has 64mb onboard, or if you run games in uber high detail and it gets really choppy - try bumping it up a bit, and it should sort you out.

 

[amneziac85]

But isn't regular ram faster than the videocard's ram??

Not by a long shot, video cards use DDR2 and I think DDR3 on newer cards...

Ignoring the fact that it isn't actually attached to the card?

If you ignore that fact, whats the point of the post?

Lets say you had a gig of PC 4200

Lets say you had 10 X800s' and your ready to plug em all in at the same time Voodoo 2 SLI style...great...now go find a mobo that supports them and youll be in business

would it be a viable alternative to GPU ram?

Viable meaning...better then the page file? Then yes. Viable meaning just as good as video ram? Then no. Thats why video cards have ram in the first place, because there is no "viable" option.

 

[RABIES]

Finally someone explains it! So what happens when a user/dummy sets it to twice his/her amount of available RAM? Does it hose?

Now if we could get an explanation of CPU thermal throttling.....lol. We know what it does, but which way does it work? I.E.: 20% TT, does it slow the CPU by 20% or make it run at 20%? And in effect, does that not make the CPU hotter becuase it is working harder when slowed down?

 

[psyno]

But isn't regular ram faster than the videocard's ram??

Not by a long shot, video cards use DDR2 and I think DDR3 on newer cards...

It's true that it's not by a long shot, but not for the reason above. Take the GF FX 5900, for example, which uses GDDR(1) RAM. It has something around 30 GB/second of memory bandwidth, while on the other hand DDR2/667 (PC5300?) configured in dual-channel operation could only reach a theoretical maximum of 10.7 GB/s, and that's just about the fastest system memory setup you can find in terms of bandwidth. Single-channel DDR400 (PC3200) using DDR1 (much more common kit, though still on the high end) has a theoretical maximum of 3.2 GB/s. Without even considering the extra latency involved, you can tell it's going to be an order of magnitude slower.
So, really, once you start using the AGP aperature, you will know it, and your play experience will be significantly degraded. IMHO it's pretty worthless. Better than swapping to be sure, but your FPS will have died already anyway.