Looking for advise on nVidia 6800 video cards

[Sky Pilot]

I've decided to upgrade my gForce 5200 with a new nVidia 6800 GT. As I've shopped for one, I've discovered many different configurations of the same card/chip set.

I've found that nVidia sells the card under their own name with a lifetime warranty, but their chip set is also installed on many other manufacturer's cards (PNY, eVGA, LeadTek, BFG, and XFX, just to name a few!). I've also seen for sale overclocked cards and cards with 400 vs 350 MHz (is this the bus speed?).

Can someone help me sort all this out? I'm not much of a gamer. My primary use for the card will be Celestia -- I'm looking to smooth the approach to celestial objects when flying toward a new hires textured body. My current card stops as I approach a new body and then jumps into view.

What should I look out for when purchasing a card? Is an overclocked card bad? Should I buy one with an aftermarket fan?

Many thanks!!

[selden]

Here are a few general comments. I'll leave it to someone else (Don Edwards?) to make more specific comments.

Don't forget that 6800 model cards need a *lot* of power and cooling. You need at least a 400 Watt power supply to be sure there's enough headroom for the card and all the other hardware in your system. The 6800 cards get power both from the motherboard slot and from an additional connection directly to the power supply that must not be shared with anything else.

The clock speed that's usually quoted is for the graphics processor itself. It controls how fast the GPU can operate on 3D models and textures.

The pauses you see mostly are caused by loading textures (and models) from disk into memory, converting them to a format the graphics card can use, and then loading them into the card. You need a faster disk, faster CPU, lots of RAM and a faster AGP bus to reduce that problem. By itself, a faster graphics card won't help very much. It'll improve the speed that you can rotate very complex models, though.

I hope this clarifies things a little.

[Harry]

The pauses you see mostly are caused by loading textures (and models) from disk into memory, converting them to a format the graphics card can use, and then loading them into the card. You need a faster disk, faster CPU, lots of RAM and a faster AGP bus to reduce that problem. By itself, a faster graphics card won't help very much.

It can help tremendously to convert most JPG and PNG textures to DDS, as these load much faster. This reduces the visual quality a bit, but is still ok as long as you leave normalmaps and bumpmaps(?) alone. Of course you may have to edit SSC files so the DDS texture get used (though most use "name.*", so it suffices to rename the original textures after conversion).

Harald

[Sky Pilot]

The pauses you see mostly are caused by loading textures (and models) from disk into memory, converting them to a format the graphics card can use, and then loading them into the card. You need a faster disk, faster CPU, lots of RAM and a faster AGP bus to reduce that problem. By itself, a faster graphics card won't help very much. It'll improve the speed that you can rotate very complex models, though.

Thanks Selden

Has anyone tried running Celestia on a Ram Disk? Sounds like that would offer a significant improvement in performance.

[selden]

Enough RAM would be rather expensive. Right now, the disk space occupied by my Celestia Addons is about 4.5GB, although the space needed for the active Addons is much smaller than that. I know other people have much larger collections.

You'd also need to have a system that can address that much memory plus the space needed by Celestia itself and other running programs. Most P4 systems can only address up to about 4GB. Xeon servers usually can address more, though.

[Sky Pilot]

I have several thematic installations of Celestia -- fictional, puristic, etc. None of them are more than 500 MB (total directory size). I'll play with this a bit and see what happens.