ATI video RAM

[judgex]

Hello,

How much system RAM is taken as video RAM by the ATI fglrx driver on Linux. Is it half of total system RAM or is this controlled by BIOS?

 

[nagash]

i really didnt understand the question but if your video card is ati (its not onboard video card) so answer is none.

 

[AlephNul]

No system RAM is used as video RAM by most video cards - they almost always have video RAM on the card. It's usually only motherboard video that uses system RAM.

Look up your video card and you'll find out how much video RAM is provided on the card.

 

[jyjjy]

Yeah, for a discreet card it should use no system ram(with rare exceptions.) If it is onboard video then the amount of ram used is usually set in the motherboard's BIOS.

 

[judgex]

i really didnt understand the question but if your video card is ati (its not onboard video card) so answer is none.

Thanks for the reply. Yes the ATI video card on PCI Express and has 128MB dedicated memory. It is not an integrated graphics solution.

 

[judgex]

The board is a "ATI Radeon™ E2400 PCI Express® Board":

http://www.amd.com/us/products/embedded/graphics-processors/Pages/ati-radeon-e2400-pci.aspx

 

[jyjjy]

Hmm, never even heard of that card. Still it does have 128mb of memory and I don't see any mention of the ability to add to that with system memory.

 

[judgex]

I found a page that explains video RAM memory bandwidth. It isn't exactly what I was looking for but it has a section called "HyperMemory and TurboCache".

http://www.playtool.com/pages/vramwidth/width.html

This section explains:

Both ATI and NVIDIA (two large GPU makers) have designed low-end video cards which complicate the whole memory bandwidth issue. NVIDIA's implementation is called TurboCache. ATI's is called HyperMemory. Cards which implement TurboCache are often called "TC" models and HyperMemory is often shortened to "HM". You need to watch out for these kinds of cards because their memory systems are very different from most video cards.

Both of these kinds of video cards borrow RAM from the motherboard to use as video RAM. These video cards have a total useable amount of RAM which is the sum of both the video RAM actually on the video card plus the RAM borrowed from the motherboard. These cards are produced because it's cheaper to borrow RAM from the motherboard than it is to include "real" video RAM on the video card."

The ATI Radeon™ E2400 PCI Express® Board could be borrowing memory from the motherboard to supplement its 128MB dedicated video RAM. Is it true the total memory borrowed from the motherboard cannot exceed half the System RAM? How does one control the amount of memory borrowed from the motherboard? Is it a BIOS setting or does the video card driver do it automatically?