Question about memory interface and directX

[Xitij]

i have 2 questions...

1)
I was wondering what the difference between different memory interfaces on video cards is? I've seen cards with memory interfaces from 128 bits to 320 bits. How does this if at all relate to performance.

2)
basically the only cards that can run directX 10 are directX 10 cards. In other words if you get a DirectX 9 card, and a game uses Direct X 10 you can download it (DX10) but your hardware won't support it and you will be stuck running DirectX 9. Is this true? Will this be a big issue running DX10 games on DX9 cards?

thanks

Xitij

 

[kitchenshark]

Answers

1) Memory bus width is similar to a freeway. The wider the bus, the more lanes it has, the higher the available bandwidth. More bandwidth, faster communication between the GPU and its memory.

2) It's my understanding that DX10 games will be playable on DX9 cards, but with some of the graphics features disabled. Though there will probably be some DX10 games that won't play at all on DX9 hardware.

 

[Xitij]

ok thanks a lot...based on your answers

1) would it be better to get a card with larger memory interface or a card with faster memory clock. is one more important than the other or do they basically increase hand in hand.
will there ever be cards with 128 bit interface and 1600 MHz clock vs a clock of 1500 MHz and 256 bit interface. I guess if it is the way i think it is you can just use simple math to figure out which can transfer more bits (and therefore data) in a given amount of time (is this correct?).

2) do you think its worth getting a DX9 card now, or just wait for more DX10 cards to be released and wait for my price range?

it be impossible to upgrade DX9 hardware to DX10 so all the features of a game might not be available, so i will have to upgrade any ways, seems kind of pointless to me.

 

[PCAnalyst]

ok thanks a lot...based on your answers

1) would it be better to get a card with larger memory interface or a card with faster memory clock. is one more important than the other or do they basically increase hand in hand.
will there ever be cards with 128 bit interface and 1600 MHz clock vs a clock of 1500 MHz and 256 bit interface. I guess if it is the way i think it is you can just use simple math to figure out which can transfer more bits (and therefore data) in a given amount of time (is this correct?).

2) do you think its worth getting a DX9 card now, or just wait for more DX10 cards to be released and wait for my price range?

it be impossible to upgrade DX9 hardware to DX10 so all the features of a game might not be available, so i will have to upgrade any ways, seems kind of pointless to me.

First and foremost... do you have or are you getting Windows Vista?

Vista is the only OS that supports Direct3D 10.

If you download a lot of movies and music... you may not want Vista.

With that said... Current DX10 cards are vastly superior to all other cards out.

Nvidia will release lesser cards in the near future that will still run DX 10.

AMD/ATI is releasing the R600 in March... it is supposed to be/ rumored to be a better GPU than Nvidias card.

If you absolutely are not interested in Vista for at least a year... then a 1900GT or 1950XTX are great cards. So is the 7950GT or 7950GX2 - which are not DX10 cards... but will play DX10 games for some time to come.

If you are on a budget... a recent model is suggested but it is not necessary to spend a ton of money for the 8800 series right now.

Epic Games (Creators of Gears of War & My Fave... Unreal Tournament III) have designed thier new games for DX10... and in an interview with the producer Mark Reins from Epic - all upcoming DX10 games this year will run on DX 9

So it boils down to budget and choice... your choice.

 

[kitchenshark]

You're welcome. =)

I unfortunately don't have the time (about bedtime for me) to do the research necessary to give you an informed answer on which exactly is better between wider bus or faster memory, but I'll give you my observations.

They are both rather important. A narrower bus can be a critical handicap on a card. However a high memory clock can overcome the narrow width to an extent. The easiest way that I've been able to tell the difference between cards is looking at comparitive benchmarks at sites such as Toms Hardware. The numbers aren't as important as is the relative performance to another card. Definitely peruse the following:

http://www23.tomshardware.com/graphics.html

As for waiting for DX10...me personally I'm sticking with my GeForce 7600 GT until I see a nice DX10 card I like. It plays all the games I like (Doom3, HL2, etc) with respectable settings. I believe a 7600GT will only set you back about $120 USD. Which is pretty good bang for your buck.

Edit: Apologies for the rambling...it's late here and just got home. I agree with PCAnalyst too.