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video card specs questions...

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November 16, 2004 5:43:20 AM

I there! I've been reading a lot of stuff and reviews both here on THG and at many other sites regarding video cards and there specs. I'm planning on buying a new video card soon, sometime in the next few months, because the Radeon X300 that came with my new desktop isn't going to cut it with the new games coming out soon (it barely does a satisfactory job on Battlefield Vietnam, which is not that graphics intensive).

I have found many articles and reviews, especially this forums guide to which current video cards are good, to be very helpful. At the moment, I'm leaning more towards the nVidia GeForce 6800 GT or the 6600 GT, but the vanilla 6800 and the Radeon X700 XT are close behind in my considerations.

However, there are certain aspects of the video cards that I'd like to know more about before making a purchase.

1. Video card specs include things like core and memory speed, memory interface, memory type (DDR, DDRII, GDDR3, see question 2 below), memory size, pixel and vertex shader version, and the number of pixel and vertex pipelines. I'd like to know which of these specs is most important and which is the least (ie. which specs are more likely to create bottlenecks for your system and which ones will better allow you take full advantage of the hardware)?

2. What is the difference between DDR, DDRII, and GDDR3 memory and how important is which one you get?

3. I've heard that certain cards have specs that act as bottlenecks and don't allow the card, or the system, to take full advantage of all available vRAM (e.g. having a 64-bit memory interface). When is it, if ever, better to get 256 MB of vRAM instead of 128? Are there any particular cards out there that needlessly have 256 RAM simply as a way of jacking the up it's price?

4. I've also heard that despite DirectX 9.0's existence, many current games still operate mostly on older DX versions (e.g. UT2004). Is the same true for the vertex and pixel shader versions?

5. As you may have guessed, I'm buying my video card for use mostly, if not exclusively, for games. However, after hearing reports that the Radeon X800 chipset doesn't support tri-linear filtering, I scratched them off my list of considerations. Am I being too brash here, or is there a real issue here with ATI's sneaky practice?

If you guys can give me any help with these questions, it'd be much appreciated. Thanks.


Mad Cat
:D 
November 16, 2004 8:13:56 AM

With all the cards u mentioned, u will be getting GDDR3 memory unless specified.
DDR - double data rate. its a kind of SDram where data is sent over the bus over the falling AND rising edge of the clock pulse. Its synchronous, ie synchronizes its data transfer with the bus clock. DDR2, is now coming to system main memory. G mean graphics and all the memories u listed are derivatives of DDR. You shld be just concerned with getting GDDR3.

Core speed is the speed of the GPU core - Hz
Memory speed is the speed of the memory - Hz

If memory speed it X Hz, DDR makes it 2X Hz as I said, it was double.....

DDR2, isnt performaing as well as DDR1 these days bcos lack of fast DDR2 and Intel creating a bull$hit memory interface. But as U r interested in graphics card only - u gotta only look for GDDR3. Others are system meory or old card memories.

Vertex an pixel shaders have version just like DX. If a card doesnt support version 3, then its gonna support something else. Again - only ones now supporting PS3.0 are the ones u listed except X700. A game will operate on oolder DX mode if it feels u have a fuc*ked up card to handle extreme stuff. Best ex: Half-life 2 (that I am playing now :smile: ). See review from firing squad about it.

Main thing is - how much are u willing to spend on graphics card ?

get

No limits: X800XT PE
300-400: 6800GT factory Oced

those both will be AGP and PCIe.

<300:
X700XT/PRO is currently only PCIe. 6600GT is again PCIe, but u ll see the AGP ones in market soon.

<175:
R9800pro/XT


BTW, y did u name urself madcat ?
funny, my library here uses that name for catalogs.

:tongue: <A HREF="http://www.geocities.com/priyajeet/fing.jpg" target="_new"><i><font color=red>Very funny, Scotty.</font color=red><font color=blue> Now beam down my clothes.</font color=blue></i></A> :tongue:
November 16, 2004 4:02:47 PM

1.
The most important spec of a videocard is it's number of pixel pipelines, but the core (or GPU) speed ties in heavily with this, because the number of pixels a videocard can process per second is pipelines x core speed.

Your X300 has four pipelines, for arguments sake let's say it's running at 200 mhz. 200x4= 800 megapixels per second...
My 9700 PRO has 8 pipelines, let's say it's running at 200 mhz, too. it'll process 200x8= 1600 megapixels per second...
Now, if you overclock your 200 mhz X300 to, say, double it's stock speed... 400mhz, you'll be pushing 1600 megapixels as well. But it still won't be quite as speedy as an 8 pipeline card for other efficiency reasons that I won't write a 6 page essay on, but the point is that chip speed in Mhz is important, and can be an equalizer for cards with fewer pipelines.

Second most important is memory bandwidth. This is affected by 2 things; Memory SPEED and mamory BUS INTERFACE.
(The AMOUNT of memory is almost entirely irrelevant, but that's covered below)
Memory SPEED is measured, once again, in Mhz. The faster the better.
memory INTERFACE is measured in bits. In a way, this is similar to the pipelines in the graphics processor, because 128-bit memory will deliver twice the bandwidth of 64-bit memory at the same Mhz. 256-bit memory will deliver four times the bandwidth of 64-bit memory at the same Mhz!

This is why video cards with 64-bit memory are so useless. Even if you run the memory at superhigh speeds, it's not going to perform.64-bit memory at 1000 Mhz has the same bandwidth as 256-bit memory at 250 Mhz!

THE LEAST IMPORTANT IS THE AMOUNT OF MEMORY. An 8 pipeline card @ 200mhz with 64 megs of memory is preferable to a 4-pipeline card @ 200 Mhz with 256 megs of RAM. Memory SPEED is important, but memory AMOUNT does almost nothing for performance. What it DOES do is allow you to use higher-detail texture sets however, and while all games still support 64-meg texture sets, some of the newer ones like doom3 will have more detail in the textures if you have the RAM. But the downside is, if your card is too slow to use that high detail level, that huge amount of RAM is wasted.
RAM also helps a bit at high resolutions and with higher levels of Antialiassing, but once again, if your card is slow in the first place, all that RAM is useless.

Everything else falls in between, Vertex and Pixel shader version is tied in to the directX version that a card can hardware-accelerate... if it's a true DirectX 9 card you're OK. The new Geforces are DirectX 9.1 compliant, which hasn't really made a difference yet and it looks like it's not going to make a big impact, so basic DirectX 9 is what you're looking for, but if you get a card that has Dx9.1, great. But I certainly wouldn't buy based on that alone.

2. DDR is usually slower than GDDR2 is usually slower than GDDR3. But this is measured in Mhz, so the type isn't as important as the advertised memory speed (in MHZ)

One thing about memory... because it's all DDR now...(double data rate, memory can do twice the work per clock cycle that old single data rate memory could) some manufacturers will advertise a 200 Mhz DDR as "400 Mhz effective. Be wary of this.

3.
I covered this in #1.

4.
It's true, all directX 9 games today use mostly DirectX 8 shaders, with a few DirectX 9 shaders thrown in for the really fancy stuff.

DirectX 8 was the big bump, as DirectX 7 didn't have programmable shaders at all... DirectX 7 couldn't do those nifty water effects and stuff.

Still, if you're buying now, get a DX9 card. Dx9 shaders will only be used more and more.

5.
Both Ati and Nvidia have "adaptive" filtering techniques that aren't true trilinear (actually Nvidia started this practice, not Ati).
Frankly, you won't see the difference in gameplay because they do a good job of maximizing performance.
Still, with Ati's Catalyst AI driver I believe you can turn them off, I think you can turn them off in Nvidia's drivers as well, so this isn't really an issue anymore. If you heard it was Ati-only, it was probably some ignorant Nvidia-fanboy. :) 

Hope this helps,

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November 17, 2004 3:39:10 AM

Cleeve, Priyajeet, I'd like to thank you very much. You two basically told me what I needed to know. Your information will be invaluable when I buy a new card, so thanks again.

To answer Priyajeet's question regarding my name: when I was 11, my grandmother bought me this plush toy cat that I fell in love with immediately. I used to play around with him all the time. One day, during the Mad Cow disease scare days, my dad commented that I had Mad Cat disease, because even in my late teens I still thought my plush toy cat was really keen. As such, I named myself Mad Cat in online forums. The added incentive, of course, is that the Mad Cat is a totally kick-ass Mech in Mechwarrior/Battletech :p  The 2099 in my name, which is a reference to Marvel Comic's now defunct 2099 line of comics, was added because someone is apparently already registered as Mad Cat.

In any case, I just one further question: Does the amount of vertex pipelines matter so much, or is it just mainly the pixel pipelines that are key? I only ask because that's one of the main differences between the X700 and 6600 chipsets; the X700 has all six, whereas the 6600 series only has 3.


Mad Cat
:D 
November 17, 2004 1:29:52 PM

Pixel Pipelines are more important than Vertex Pipelines.

Pixel pipelines are used in every pixel displayed.

vertex pipelines are of limited benefit, and only make a difference in games that rely on TONS of geometry. I suspect games like warhammer 40k and the upcoming battle for middle earth will take advantage of more vertex pipelines more than the usual game because of all of the 3d models on screen at the same time.

________________
<b>Radeon <font color=red>9700 PRO</b></font color=red> <i>(o/c 332/345)</i>
<b>AthlonXP <font color=red>3200+</b></font color=red> <i>(Barton 2500+ o/c 400 FSB)</i>
<b>3dMark03: <font color=red>5,354</b>
a b U Graphics card
November 17, 2004 3:21:33 PM

However Vertex shaders are being used more and more.

<A HREF="http://graphics.tomshardware.com/graphic/20031015/radeo..." target="_new">X2 actually uses no pixel shaders</A>, only Vertex shaders. And the impact of VS3.0 has more potential than PS3.0. Also Vertex shader pipelines can be used to complement Pixel pipelines and do things like displacement mapping and instancing. 3Dmk05 will stressing Vertex Shaders far beyond what games are expected to, does also point towards a bit more focus in the future. Just the grass effect efficiencies in FartCry are pretty impressive. Sure the pixelpipelines will be the biggest factor, but the vertex shaders in some games will break ties or bring forth unexpected winners.

The most interesting example of differences is in some GF6800 cards where the pixel pipeline number, and relative clock frequencies of the cards are the same, but one has 1 or more vertex shaders dissabled to make it a 'lesser' model card. It clearly shows what areas the vertex engine impact and that they do play a significant enough role.

Focus, still on Pixel-pipelines first, but don't forget the vertex engines when looking at the whole picture.


- You need a licence to buy a gun, but they'll sell anyone a stamp <i>(or internet account)</i> ! - <font color=green>RED </font color=green> <font color=red> GREEN</font color=red> GA to SK :evil: 
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