Does overclocking a video card make a difference for video encoding/decoding?

[xMax]

Will the higher clock speeds in a card like the "eVGA 7900GTX SUPERCLOCKED" actually be used for the encoding and decoding of videos?

Another words, would the "eVGA 7900GTX SUPERCLOCKED" and the "eVGA 7900GTX EGS" run at the same clock speeds when used for encoding/decoding and video playback, even when they have different clock speeds?

Im asking because many or all of the ATI cards, when overclocked, will only use those overclocked core and memory clock speeds for 3D games and not for 2D applications like encoding/decoding and video playback.

I have also heard that all cards run at different speeds when used for 3D and 2D. That is, they will always run at a lower clock speed for 2D than they will for 3D, which means that two differently clocked cards like the 'superclocked' and 'egs' eVGA cards may still run at the same lower clock speeds for 2D.

So im a little confused. Any ideas, even general ones, would be helpful.

Thanks.

 

[Regs]

I believe it's all done using the video cards RAMDAC

400MHz is the top speed I think.

 

[rbV5]

Im asking because many or all of the ATI cards, when overclocked, will only use those overclocked core and memory clock speeds for 3D games and not for 2D applications like encoding/decoding and video playback.

3rd party utilities allow you to overclock Radeon 2D/3D clocks, however video acceleration is a function of the 3D shader pipeline in a supported application, if you want the card to run overclcked no matter what application you run...overclock the card with something other than ATI's overdrive. Not so different than using the 2D/3D clocks with a Nvidia card and coolbits is it?

Whether overclcocking helps accelerate video depends on how much the GPU is helping accelerate th video in the first place. If its used very little, overclocking is likely not to help much.

Nvidia cards use the onboard video processor (which runs independant clockspeed of the GPU (allegedly) as well as the shader pipeline to help accelerate some compressed formats like MPEG and H264. So I suppose there could be some small benefit, but I doubt much when you are talking the difference between 2) 7900 cards. GPU Clockspeed makes a difference on Nvidia cards judging by the difference in decoding H264 with the different Nvidia GPU families, but not so much on the same core I suspect.

Encoding will see no benefit since hardware acceleration isn't supported on Nvidia GPU's. Overclcoking your CPU definately will provide some benefit however.

 

[xtknight]

Possibly for decoding. Here is my post from another thread.

Originally posted by: xtknight
Since I didn't mention it earlier, I'm using da_vinci_code-tsr2_h1080p.mov (The Da Vinci Code Teaser 1080p) (150 seconds in duration).

This time I downclocked my eVGA 7800GT from stock 445/535 MHz (445/1070 MHz effective) to 300/535 MHz (300/1070 MHz effective) and 445/360 MHz (445/720 MHz effective).

H.264 - No Hardware Acceleration
H.264 - Hardware Acceleration - Stock Clocks (445/535)
H.264 - Hardware Acceleration - Lower Core (300/535)
H.264 - Hardware Acceleration - Lower Memory (445/360)

It looks like lowering the core speed actually did something. The memory speed didn't matter. That was the opposite of what I would have thought. Interesting.

 

[rbV5]

Originally posted by: xtknight
Possibly for decoding. Here is my post from another thread.

Originally posted by: xtknight
Since I didn't mention it earlier, I'm using da_vinci_code-tsr2_h1080p.mov (The Da Vinci Code Teaser 1080p) (150 seconds in duration).

This time I downclocked my eVGA 7800GT from stock 445/535 MHz (445/1070 MHz effective) to 300/535 MHz (300/1070 MHz effective) and 445/360 MHz (445/720 MHz effective).

H.264 - No Hardware Acceleration
H.264 - Hardware Acceleration - Stock Clocks (445/535)
H.264 - Hardware Acceleration - Lower Core (300/535)
H.264 - Hardware Acceleration - Lower Memory (445/360)

It looks like lowering the core speed actually did something. The memory speed didn't matter. That was the opposite of what I would have thought. Interesting.

Extreme downclocking reduces the acceleration, sure. How about your card stock vs OVERclocked? Do you see much benefit from a likely overclcock? I see very little benefit with my Radeon cards (if any) when overclocked, and I suspect the Radeon cards advantage the GPU's shaders more than the Nvidia cards do.

 

[xtknight]

Since I didn't notice much difference playback-wise even with the extreme downclock, probably not with a subtle overclock, but maybe 5%. I don't have a custom heatsink and typically the 7800GT has quite a low clock ceiling so I don't want to risk it in any way to test as the acceleration is enough for 1080p already.

 

[xMax]

So overclocking could make a difference, as the amount depends on many hardware and software factors that are extremely difficult to understand.

The only simple conclusion is to take the fastest and be assured that im getting the best and therefore doing the best i could.

But at the same time, to imagine the non-overclocked version of the 7900GTX not having the required performance seems erroneous.

But if i have the money...Hmm

 

[xtknight]

Well it's certainly no difference you'd want to spend extra for, that's for sure, at least IMO.

 

[xMax]

Are you in some kind of a hurry xtknight?

Because your last reply is difficult to comprehend.

Is english a second language to you?

Because if it is, then my apologies.

I mean it could be comprehended, but its just not exactly crystal clear, like the way i write.

Don't get me wrong! I'm not saying i'm more intelligent than anybody. I'm simply saying that i put an effort to being as clear as possible when writing. I actually reread my replies in order to make sure the spelling and grammar is reasonably proper.

I cant stand it when people write so recklessly because they are too lazy to reread their reply just once.

 

[xtknight]

Originally posted by: xMax
Are you in some kind of a hurry xtknight?

Because your last reply is difficult to comprehend.

Is english a second language to you?

Because if it is, then my apologies.

I mean it could be comprehended, but its just not exactly crystal clear, like the way i write.

LOL, no I am not an ESLer, but I do use a subconscious shorthand and get lazy. Sorry, it was a bit unclear. The difference I mean is between stock 7900GTX and overclocked 7900GTX but I forgot to clarify that. I talk to a friend on AIM that's like that all the time-he doesn't clarify things and I also get annoyed.

Anyhow, it seems like you have been looking for a video card for quite a while now with all these threads. What's your current situation? Is this still for watching uncompressed AVI videos? If so, the video card will not affect uncompressed videos. The burden is then placed upon your system's memory bandwidth and size.

Edit: clarifications.

 

[xMax]

Yeah im still looking for a video card. It's absolutely insane what i have been going through with this video card issue. Every other computer component that makes up my entire system, which includes the monitor and all other components not found in the tower, have essentially been bought once and work perfectly. Except for the video card. I have been through 4 on my new system.

But i cant possibly explain my entire situation right now.

Im not trying to be rude, but it's really taken its toll on me, and i just quickly lose motivation and energy when talking about it.

I can only say that i'm going to pass up on the overclocked version of the 7900GTX.

I have to go now.

Thank's for helping me out in whatever way you could.