Video card dilemma

General discussion about Celestia that doesn't fit into other forums.
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danielj
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Video card dilemma

Post #1by danielj » 08.07.2005, 14:06

I don??t have money to buy a Geforce 6800 GT,so I have to choose between a Geforce 6800 and a Geforce 6600 GT.But the Geforce 6800 256 MB is beaten by the 6600 GT 128 MB,because it??s slower.So,if I want the biggest textures and no slowdown in Celestia.I should prefer more speed or more video memory?Remembering that GF 6800 have 12 pipelines and GF 6600 GT have 8,altough I don??t know if it??s important.
PS:Actually,it was this that I wanted to ask,in the first place

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selden
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Post #2by selden » 08.07.2005, 15:37

Daniel,

That's the tradeoff that you have to decide on your own: cost versus performance versus capacity. A 6800 (at the same clock speed) should be about 50% faster than a 6600 GT at drawing and rotating models. As best I can tell from the benchmark pages I've seen, though, 6600GT and 6800/256M performance are almost identical. Although it has a slower clock, the extra shaders and wider memory path give the 6800 more speed. If you have lots of large textures and models loaded, then more memory is more important than speed. This speed won't make Addons load faster, though. For that you need faster CPU and disk.

Also, don't forget that a 6800 uses *lots* of power. It has an extra power connection on it because the motherboard socket can't supply all the power it needs. It runs very hot and needs lots of cooling and a system power supply of at least 450Watts. A 6600GT doesn't need or have that second connector, although it also runs rather warm when it's doing 3D graphics.

(I have a 6600GT in my "new" system.)
Selden

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danielj
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Post #3by danielj » 08.07.2005, 16:46

And what trade-off did you choose?Is your 6600 GT 128 MB or 256 MB?
Other thing is that it??s funny to say that CPU and HD influence the frame rate,because fridger said the only thing it??s really matter is the video card.

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t00fri
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Post #4by t00fri » 08.07.2005, 17:01

danielj wrote:And what trade-off did you choose?Is your 6600 GT 128 MB or 256 MB?
Other thing is that it??s funny to say that CPU and HD influence the frame rate,because fridger said the only thing it??s really matter is the video card.


That's a bit oversimplified citation. It is correct for a Celestia user like myself and also assuming that you have a /decent/ CPU speed above some reasonable minimum.

I practically never deal with add-ons for example. You use lots of them, in contrast. Moreover in all the computers that I built (and that's quite a few meanwhile) I put very much emphasis on a /fast/ HD. Sure enough, all these hardware components affect to some extent the overall performance. But if you make an importance hierarchy, then it reads for /Celestia/:

1) graphics card + video ram
2) HD performance (<======VT's !!!)
3) CPU speed

You should also not forget that I am a scientist in theoretical physics and hence use my machines /mostly/ for very demanding computational tasks besides Celestia. So Celestia for my computers is just a small additional constraint...

For my "demanding calculations" the hierarchy is almost reverted:

1) CPU speed + lots of RAM
2) HD performance (both access time & speed)
....


5) graphics card + video ram


Bye Fridger

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selden
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Post #5by selden » 08.07.2005, 18:16

When I got my new system about 6 months ago, the 6600GT was only available with 128MB and most other 6xxx cards were out of stock.

Note that I said that Addon load time is affected by HD and CPU performance, not frame rate. Celestia pauses while it's reading textures from the disk, though, so new frames are not drawn then, and the CPU is used to translate JPEG and PNG images into a format that the graphics card understands. Larger images take longer.
Selden


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