Two Questions Regarding System Memory

xenomouse

The first question may be a matter of opinion (professional or otherwise). I Googled the second but could not find a straight forward answer.

I've never had any problems in the quality of RAM that I've bought, but I know that nowadays, with DDR2, computers are more sensitive to RAM issues. Are there particular brands to avoid? Can I assume that buying RAM with good reviews on Newegg is safe, regardless of brand?
I know there is some amount of RAM that Windows XP Pro can recognize before you need to start fiddling with the system settings. That limit seems to be around 4GB. What's the fiddling that needs to be done?

Apreche

I've never had any problems in the quality of RAM that I've bought, but I know that nowadays, with DDR2, computers are more sensitive to RAM issues. Are there particular brands to avoid? Can I assume that buying RAM with good reviews on Newegg is safe, regardless of brand?I know there is some amount of RAM that Windows XP Pro can recognize before you need to start fiddling with the system settings. That limit seems to be around 4GB. What's the fiddling that needs to be done?

1) RAM either works or it doesn't. Sticks are either good or bad. Shittier sticks might go bad, but there's nothing you can do about that. If you are really anal and crazy, you can pay a premium to get name-brand RAM. if you are smart, you will just buy the cheapest RAM that is the type and speed you need. In the rare case that the RAM doesn't work, get an RMA. The price difference is big enough for the potential hassle to be worth it.

2) If you are using a 32-bit processor or a 32-bit operating system you can only have 4 gigabytes of RAM because that's all you can address with 32 bits. I know in Linux there are things you can do if you wan to use more than 4 gigs of RAM on a 32-bit system, so I assume you can do things in Windows as well. However, 4 gigs of RAM on a 32 bit system is more than any consumer should need at this point in time for absolutely anything. If you really want to have a badass server that actually needs more than 4 gigs, get 64-bit chips and a 64-bit OS.

Omnutia

It's 3.58 gbits I think; For 32 bit systems that is.
I wish I could afford a couple gigs of ram to run windows in Innotek Virtual Box.

xenomouse

Just a follow-up: does a heat spreader make any difference, or is it one of those things I won't notice unless over-clocking?

Katsu

As far as I have been able to determine through my own experience, they aren't really needed unless you either are in a room with poor ventilation and it heats up to high temperatures consistently or the case's internal temperature is high normally.

xenomouse

Well, I'm lucky enough to have a cool-running CPU.

Omnutia

As long as you have some air flowing past the ram you should be fine. The heat spreaders are one of those things that, if you don't know why you need it, you don't need it. (we need a word to express that as its becoming increasingly common. I suggest DKDN "don't know, don't need")

Usagimaru

That limit seems to be around 4GB. What's the fiddling that needs to be done?



If your thinking of getting 4GB of RAM, and have a 32-bit system, you also have to factor in the memory that's used from your graphics cards. If you buy 4GB of RAM, then you have 3.58GB on a 32-bit windows, and then you need to take out the memory used on the graphics card, that is recognized by the system. So if you have a 512MB graphics card, then you are getting 3.08GB of system memory.

Apreche

If your thinking of getting 4GB of RAM, and have a 32-bit system, you also have to factor in the memory that's used from your graphics cards. If you buy 4GB of RAM, then you have 3.58GB on a 32-bit windows, and then you need to take out the memory used on the graphics card, that is recognized by the system. So if you have a 512MB graphics card, then you are getting 3.08GB of system memory.

Um, no. You are completely wrong. a 512MB graphics card has 512MB of RAM on it. That's why it costs so much money. The only times a graphics card uses your system RAM is if you set an AGP aperture in the BIOS or if it is an on-board graphics card that doesn't have its own RAM. If you have a 512MB card, you can probably set your aperture to 0. Now, if you have a video card with less RAM on it, you might want to up the aperture, and that will lose you some RAM, but not much.

Symmetry

He's not talking about the graphics card using up the system RAM, he's talking about the graphics card using up a 512MB slot in the system's memory addressing space. The place where the 4GB limit is.

Rym

... he's talking about the graphics card using up a 512MB slot in the system's memory addressing space. The place where the 4GB limit is.
But that memory isn't addressed by the system: it's addressed by the video card itself.

Apreche

... he's talking about the graphics card using up a 512MB slot in the system'smemory addressing space. The place where the 4GB limit is.

But that memory isn't addressed by the system: it's addressed by the video card itself.

Well... I guess it depends. It is technologically possible to do it either way. It is possible to have an architecture where the system RAM and the video RAM occupy the same address space. It is also possible to design a system where they occupy two different address spaces. Everything I know about computers tells me that they occupy two different address spaces in any modern PC. However, on a 64-bit PC where there is address space to spare, I can see some advantages to putting the video RAM in the main address table. I still probably wouldn't design it that way, even on a 64-bit PC, but an argument could be made.

HMTKSteve

If you have the option of using a vdeio card with 256MB of RAM OR an onboard video that uses 256MB of system RAM which is better performance wise? For the purpose of this question both systems use the same exact GPU and there is system RAM to spare.

Apreche

If you have the option of using a vdeio card with 256MB of RAM OR an onboard video that uses 256MB of system RAM which is better performance wise? For the purpose of this question both systems use the same exact GPU and there is system RAM to spare.

Let's say you have a PCIX x16 card. That means that card has a direct link to the system RAM at a speed 16 times faster than the speed of the standard PCI bus. That's fast. Without AGP technology, for a video card to use system RAM it would have had to burden the CPU and could have only used the system RAM at 1x PCI speeds.

As fast as that is, it is still faster to just have the memory on your video card. If the memory is on the video card itself, it will always be faster than the video card having to communicate across a bus, even an accelerated direct bus, to talk to the RAM.

Memory on the video card is faster. Period. However, that doesn't mean you should ignore the ability to use system memory with an integrated gpu. It is a huge way to save a shitton of money when building a machine. Also, while having memory on the video card is faster, using system memory is fast enough in most cases.

xenomouse

Also, while having memory on the video card is faster, using system memory is fast enough in most cases.Out of curiosity, what are your thoughts on "shared memory" video cards - the ones that have 64MB on board but are listed as "effective 256MB?"

Apreche

Out of curiosity, what are your thoughts on "shared memory" video cards - the ones that have 64MB on board but are listed as "effective 256MB?"

I've never seen a card advertised this way. if they are advertising this way, it's blatantly false. The "effective" memory depends entirely on the setting in the BIOS of the PC.

xenomouse

I've never seen a card advertised this way. if they are advertising this way, it's blatantly false.Sorry, I forgot the proper marketing term: TurboCache. I have one of them in my current box - specifically, the 6200 TC PCIE version "supporting 256 MiB, including 64 MiB of local TurboCache (64-bit)."

Apreche

I've never seen a card advertised this way. if they are advertising this way, it's blatantly false.

Sorry, I forgot the proper marketing term:TurboCache. I have one of them in my current box - specifically, the6200 TC PCIEversion "supporting 256 MiB, including 64 MiB of local TurboCache (64-bit)."

Ah, now that I have read I can see how this works. If you have an IGP, built into your motherboard, it has no memory of its own. It only uses system memory. This "Turbocache" is basically IGP plus some. They put a tiny bit of video memory on the board next to the IGP, so it can use that. Then it uses the system memory for everything else. This should actually be a hell of a lot faster than using only system memory for the IGP, and a hell of a lot cheaper than actually getting a serious amount of memory on the video card. All this is saying is that a little bit of memory for the video is a hell of a lot better than none at all.

Also, I finally found the answer. Video memory does have a separate address space. GART (graphics address remapping table) is an acronym I had heard many times, but had never actually bothered to learn about until now. Somewhat obviously, it is a table in which system memory is mapped into the video memory address space. You can have 4 gigs of system RAM and then a pile of video RAM with no problems.

Usagimaru

Also, I finally found the answer. Video memory does have a separate address space. GART (graphics address remapping table) is an acronym I had heard many times, but had never actually bothered to learn about until now. Somewhat obviously, it is a table in which system memory is mapped into the video memory address space. You can have 4 gigs of system RAM and then a pile of video RAM with no problems.

I didn't look this up myself before, but in one of my computer classes we were looking at the SLI graphics charts from Tom's Hardware. So I asked why the 8800GTS 320MB cards are getting better FPS than the 8800GTX 640MB. He said that it's because they're using Windows XP still, and it starts to recognize less system memory as you have more graphics memory.
I dunno, maybe my teacher is wrong?
DKDN! lol

Apreche

I didn't look this up myself before, but in one of my computer classes we were looking at theSLI graphics charts from Tom's Hardware. So I asked why the 8800GTS 320MB cards are getting better FPS than the 8800GTX 640MB. He said that it's because they're using Windows XP still, and it starts to recognize less system memory as you have more graphics memory.I dunno, maybe my teacher is wrong?DKDN! lol

There are lots of charts there. If you look at the 3DMark chart you will see pretty clearly which card is superior. A benchmark like 3DMark will push the hardware to the absolute limit, making use of every feature available to the maximum. This amplifies the differences between hardware so that you can more easily see which are better than others. In a real world situation like playing a game, the difference in performance relies on many more factors and a much larger margin of error. This should teach you a few things.

1) It is stupid to buy the most expensive of cards because outside of benchmarks it will get you maybe one or two fps here and there, and sometimes even 1 or 2 fps less. SLI is also a waste of money.

2) Even if one card has twice the benchmark score of another card, that has nothing to do with how well that card will actually perform in real world conditions. Treat charts like these as general guides, but never as hard facts.

3) Just buy the cheapest card you can find that is powerful enough for what you want to do. Ignore all the bs.

Omnutia

A question about video RAM: As I have a laptop there is very little chance of upgrading the graphics so If I got some more ram could I then tell the computer to use some of that for video and if so would there be any significant performance gain?

Apreche

A question about video RAM: As I have a laptop there is very little chance of upgrading the graphics so If I got some more ram could I then tell the computer to use some of that for video and if so would there be any significant performance gain?

My laptop has an Intel hda video card. I just checked in the BIOS, and there is no option to configure the aperture. If your BIOS does allow you to configure the aperture, you may or may not be able to get a performance gain. Here is how to figure that out.

Run whatever game you plan on running. How much system RAM is in use? Let's pretend you have 1 gig of ram and when you play the game, the entire 1gig is in use. Well then. Giving any more memory to the video card, not a good idea. If your computer is trying to use system RAM, and it runs out, it will use the hard drive instead. This is called swapping. Hard drives are slow. Swapping is the worst possible thing for performance you can possibly do. Now, let's say you run your game, and you find that you still have like, 400MB of RAM free while the game is running. Well, feel free to set the aperture to 256MB. However, if the game doesn't use 256MB of RAM for textures, that isn't going to help performance much. If the game only uses 64MB of video RAM, then turning on any more than 64MB of RAM for the game will not help you.

So again, it depends.