Need detailed tech. info on video mem/system Mem. 1

[jsteph]

I was wondering if anyone out there could help de-mystify the difference between video memory and the system memory.

I'm working with a photo-editing app and I need more power but I'm not sure whether to spend the money on a video card or more ram. For instance, when I'm editing a photo, obviously the app reads the disk file (say, a .jpg) into memory. Now, it's my understanding that the photo is read into Ram, but the OS (xp in this case) feeds the monitor display with the video mem (I'll call it Vram). So, when I'm actually editing the photo, are my changes being physically edited in the vram, or just the ram?

My assumption is that the editing takes place in ram, and the vram is there just to then display what's on the screen. But then it seems like there's redundant stuff going on--every change in ram then must be transferred to vram since I see the edits on the screen. Can anyone give me a technical explanation of what goes on here with regard to how the pixels are moved around?

My practical issue is that when I, say, copy/paste a section of a photo, I'm experiencing too much hourglass time. I'll do a selection, hit ctrl-c, then I get the hourglass for 8-10 seconds, then I paste--and another delay. The pictures are not huge compared to what pros might work with--these are .jpegs and they're about 15 meg, but I guess in reality they're roughly 72 Meg (they're about 4000x6000 x 24bit)--but my display is 1152x864 so the whole thing never is showing at once. Would a better video card help, or more ram? I have alot of ram--512meg, and my video card is an ati 9000 with, I think 64 meg. Could the video chip be the bottlneck here--or is the system cpu what's actually moving the pixels around? I really appreciate any insight into this...
Thanks,
--jsteph

 

[dakota81]

You've got it right; when editing the photo, the software works with the system ram; then the program transfers the changes over to the video card's ram for display (I think it might go through the OS as another step before getting to the video card). You seem to have enough memory, what are your other system specs? Have PC133 or DDR memory? DDR200 memory or DDR400?

Instead of the amount of ram, try & upgrade the speed of the ram (which unfortunately can mean mobo & cpu upgrades as well).

Leave the video card alone; it's good enough. About the only option you would have there is if you reverted back to a Matrox G series card, which then you would loose the 3D capabilities of your Radeon.

 

[jsteph]

dakota81,
Thanks for replying. My system is an AMD athelon 1600 (the actual speed says 1.05 Ghz), with 512meg ddr. I'm not sure of the speed of the ram, but my guess is that it's the slowest, because it is a biostar mobo with a via chipset--the mobo/cpu together were only $89. I guess I got what I paid for. It's looking like I'll need a new mobo/cpu. I'd really like an intel cpu with an intel chipset, but the cost for that will be high. Can you recommend a good mobo/chipset for an AMD cpu?

Also, back to the video card issue, I have some academic questions. I'm vaguely aware that the amount of vram is important for cacheing and to improve performance of games. But why? I mean, if my screen resolution is 1152x864x24bit, which is roughly 3megs for a screen of pixels, why is all that extra vram important? And how does the video card know when and how to cache? For instance, I can see with a game that there would be no editing by the user of what's onscreen, so I can vaguely see that cacheing would be useful there, but in a photo editing app, If the system ram is doing all the editing, and I only want to see onscreen what's truly there, I can't see what use all that vram is if the app isn't making use of it somehow. I guess I'm just at a loss as to what the video card's cpu actually does and how it has such an affect on performance. Like if I use the drawing tools in the app and draw a triangle, I know there are functions in the video card that know how to draw those shapes very fast. But it seems that that triangle should be drawn in system ram by the app, and not by the video card, since I may be editing the actual triangle.
Thanks...
--jsteph

 

[dakota81]

The extra ram is used for 3d graphics, the tectures that would go on each object's side is stored in the video memory. I believe the video card also can have a software routine loaded into it to handle the 3d graphic processing, so that the cpu is free to work on other processing.

But for a straight 2d environment, the graphic card pretty much just stores the pixel values in memory. Almost all of the video memory & gpu power goes unused.

There is some hardware accelleration in the 2d environment as well, such as when you pull up Media Player you're looking at an overlay. The video card takes care of the positioning & resizing of the movie. But for image editing, you really want to have the preciseness & adjustability of the software anyways; as it's assumed that the user wants quality over speed.


To your current hardware, you could definately benifit from an upgrade. The P4 architecture is very good at straight data processing, which image editing is; but AMD is cheaper and for the same price you can get several models up of an Athlon XP. To get the best out of memory performance, you should get a motherboard with the nForce2 chipset; I've always liked MSI's products, their model board is K7N2 Delta-L, though pretty much all nForce2 motherboards have great performance.

AMD's Barton's, like the XP2500+ run at fsb333 which your current cpu is fsb266, so the speed between the cpu & ram will be faster (you will be using DDR333 instead of DDR266). Lastly, check the timings on the ram stick. Timings of CL2 2-2-2-5 1T is very fast. Timings of CL3 3-3-3-7 2T is rather slow.

 

[jsteph]

dakota81,
Thanks amillion for that! I'm lucky enough to live minutes from the Global warehouse (I think it's Tiger Direct now), so I'm heading there for some shopping. They often have these Saturday cleanout sales where they put pallets & pallets of older inventory on the floor to just clear it out--with luck I'll find one of the nForce2 chipset mobo's there!
--jsteph