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Ricow
08-12-08, 08:57 PM
Hello there! I dont know if this is the right place to post it because that's a CUDA and Second Life related question. Sorry about that!

I am going to buy an 8600gt based VGA, but i am not so sure about the real memory bandwidth improvement of getting DDR3 over DDR2 in those circumstances.

A 1400Mhz 256MB DDR3 VGA costs at about 20% more than a 800Mhz 512MB DDR2 version. Both GPUs are running at the same clock speed. It will mostly be used for Monte Carlo simulation and Second Life.

So:

Is that extra bandwidth really worth at all?
Would some of them reach 30 fps in a crowded place in SL?
Power comsumption remains the same in both Video Cards?

By the way, the VGA is going to be running on an E2180 OC'd to 2.8Ghz with 4GB DDR2 800@933Mhz and a G31 based mainboard (g31m-s2l).

Thanks, everybody!

jcrox
08-12-08, 10:16 PM
I don't think it will matter much. Crowded places slowing down in SL is more likely due to internet bandwidth than anything relating to video. My 8400GS runs SL just fine so I'd say an 8600GT should do the trick when it comes to the graphics.

Ricow
08-13-08, 01:36 AM
Txs for your reply, jcrox!

Well, SL never tops out my 1200/800kbps dls actual speed in crowded places, it just uses the whole link bandwidth when i move into another island. Could that still be the reason of lagging? Usually it doesn't go beyond 8 fps (1290 X 850 mid), even in places where "Sim FPS" is set to 45 and bandwidth usage is about 300kbps. So, that's why i think the VGA may be causing the sluggsihness.

The following chart showed me how graphic heavy this game is:

http://blog.secondlife.com/2007/11/15/typical-frame-rate-performance-by-graphics-cardgpu/

But it's OK. If your 8400GS runs fine, the 8600gt must work for me too.

And what about CUDA running Monte Carlo? Should i expect more performance in memory size or memory speed?

I assume that although DDR3 memory runs at highter clocks, it should consume less power. Right?

Thanks!

rhink
08-13-08, 08:06 AM
I guess it depends on if your CUDA app is compute bound or memory bound, and also how much memory it needs (256 vs 512...). I don't know if there's difference in the core clock speeds in the cards you're listing either- but those two things (core speed, memory speed) can make a huge difference in performance.

Ricow
08-13-08, 09:14 AM
I guess it depends on if your CUDA app is compute bound or memory bound, and also how much memory it needs (256 vs 512...). I don't know if there's difference in the core clock speeds in the cards you're listing either- but those two things (core speed, memory speed) can make a huge difference in performance.

Yeah, that's what im afraid of...

If i suddenly need memory speed, i can push it up somewhat by overclocking, but if i need more memory size, there will be nothing i can do.

I'm a completelly begginer in CUDA, so i have no idea if 256MB is enough for me or not. I will not work with graphics modeling, or something. Just ALU intensive app, like math calculation, random numbers generation and stuff like that. That's why i think 256 should be enough, but i may be wrong.

Btw what happens if the VGA memory gets full? The GPGPU application crashes or it starts taking system memory like TurboCache? Because if the video card can use RAM, it's great for me as it will only get slower if i need more than 256MB, but likely not as slow as the DDR2 card assuming that as soon as i disable my onboard video, i expect to reach over 350Mhz FSB, which should bump my memory read rates up to over 7GB/s...

Thank you guys for your attention! :)

jcrox
08-13-08, 07:59 PM
Get an 8800GT, that should solve all your problems :D

http://www.newegg.com/Product/Product.aspx?Item=N82E16814121263

$120 after mail in rebate for 512MB 8800GT... that's a crazy good price

Ricow
08-14-08, 12:33 AM
Get an 8800GT, that should solve all your problems :D

... Or it shall blow my 350w PSU up and get me in even bigger troubles! :captnkill:

lol the point is that i live in Brazil, and retail price are A WAY too different here. Just to mention, a 8800GT 512MB 256bits costs at least 360 bucks (in US$). :o

I was looking for a 512 GDDR3 8600gt, but i can't find anything for a reasonable price. So yeah i guess im gonna take that 256MB model. Whatever...

Txs you all guys! :D