9600 Pro Memory Bandwidth question

[b4u]

Hi,

Looking at ATI specifications, I see:

Frame Buffer: 128Mb DDR
Memory Interface: 128-bit
Rendering Pipelines: 4
Pixel Fillrate (Gpixels/sec): 1.6
Engine Clock (MHz): 400
Memory Clock (MHz): 600
Output Connectors: VGA + TV + DVI

My questions:

The bandwidth of the GPU should be: 400*128/8=6400GB
The bandwidth of the DDR should be: 600*128/8=9600GB

[1] Are my calculations correct? Do I have some sparing Bandwidth on the DDR side? That would bring me some room to OC the core without touching the DDR settings.

[2] When someone say 400/300, the settings are related to GPU/DDR frequencies, right? (just a confirmation)


Thanks

 

[Blastman]

1] Your bandwidth calculations are correct.

2] Correct.

The 9600pro is 400/300 (DDR) and comes with 2.86ns or 3.3ns Samsung DDR. The cards with the 2.8 stuff usually cost about $20 more than the cards like the Sapphire OEM/bulk with 3.3 memory.

Here in Canada ...

retail 9600pro ... ... ... .... $255 ... (2.8ns)
OEM Sapphire 9600pro ... $ 225 ... (3.3ns)

1000/2.86ns = 350mhz which is the maximum rated speed for that memory. Usually overclocks to about 350-365.

1000/3.3ns = 300mhz which is the maximum rated speed for that memory. Usually overclocks to about 310-315


When overclocking, if you overclock both the memory and GPU 10% you can improve performance 10%. If you just turn up the GPU 10% faster you might only get (1/2) = 5% better performance. Same for only turning up just the memory speeds.

 

[b4u]

Originally posted by: Blastman
1000/2.86ns = 350mhz which is the maximum rated speed for that memory. Usually overclocks to about 350-365.

1000/3.3ns = 300mhz which is the maximum rated speed for that memory. Usually overclocks to about 310-315

Thanks for the reply

One more thing ... why the use of 1000 in the above calculations? What does it stands for?

Thanks

 

[Blastman]

One more thing ... why the use of 1000 in the above calculations? What does it stands for?

I used 1000 to change the 2.86 billionth/sec into 350 million-cycles-per-second (350MHz).

?.

ns = nanoseconds = billionth/sec.

2.86ns = 0.00000000286 seconds ? = 2.86 x 10E-9

1/2.86ns = 0.350 x 10E 9 ? or ? 0.350 GHz? (Giga = billion)

finally

1000/ 0.350 GHz = 350 MHz

...

ADD: If something cycles in 2.86ns, how many times per second does it cycle?

1sec/0.00000000286 = 350,000,000 = 350MHz ? (Mega = 1,000,000)

 

[Mingon]

0.00000000286 seconds

Are you sure?

 

[Blastman]

Originally posted by: Mingon

0.00000000286 seconds

Are you sure?

But of course.

 

[b4u]

WOW! Thanks Blastman