what makes a gfx card better.

awhir

sorry but i was wondering what is more important core clock speed or memory clock freq because i see some budget cards that are runnig at 600mhz but only have 800ghz in memory speed ?and the new card today run at 600mhz

astrofool

it depends, but generally a combination of memory speed/bandwidth and gpu speed/pixel shaders.

For example, a 100mhz gpu with 4 pixel shaders will be faster than a 300mhz gpu with 1 pixel shader.

And with memory, 100mhz on a 256bit bus will be faster than 150mhz on a 128bit bus.

Most cards are usually balanced so that the gpu speed/shaders matches that of the memory speed/bandwidth.

In general, the ??800/900 line ups are using a 256bit bus with 16/24 pixel shaders atm, and are the fastest from the two main companies (ATI and nVidia).

The ??600 of each company generally uses a 128bit bus and 4-12 shaders, but generally clocked higher than the 800/900 chips as the chips themselves contain less transistors.

awhir

astrofool wrote:

it depends, but generally a combination of memory speed/bandwidth and gpu speed/pixel shaders.

For example, a 100mhz gpu with 4 pixel shaders will be faster than a 300mhz gpu with 1 pixel shader.

And with memory, 100mhz on a 256bit bus will be faster than 150mhz on a 128bit bus.

Most cards are usually balanced so that the gpu speed/shaders matches that of the memory speed/bandwidth.

In general, the ??800/900 line ups are using a 256bit bus with 16/24 pixel shaders atm, and are the fastest from the two main companies (ATI and nVidia).

The ??600 of each company generally uses a 128bit bus and 4-12 shaders, but generally clocked higher than the 800/900 chips as the chips themselves contain less transistors.

ok thanks allout.so what makes the

1800xt 512 ram http://www.overclockers.co.uk/acatalog/X1800_Series.html

not as good as the

1900xt http://www.overclockers.co.uk/acatalog/X1900_Series.html

they seem to have all the same specs.

djmarkus

The only real way to compare the performance of gfx cards are benchmarks and 3dmark scores, and even at that the results can be skewed somewhat compared to real life situations.

uberpixie

claregalway Qs wrote:

ok thanks allout.so what makes the

1800xt 512 ram http://www.overclockers.co.uk/acatalog/X1800_Series.html

not as good as the

1900xt http://www.overclockers.co.uk/acatalog/X1900_Series.html

they seem to have all the same specs.

The x1900 has a different core to the x1800 series and the x1900 also has a lot more pixel shaders than the x1800.

8T8

Just to further expand on that the difference between X1900XT and the X1800XT is that the X1900XT and XTX is a refinement of the X1800XT core.

It has been shrunk to improve manufacturing yields and clock speeds but they also upped the number of pixel shaders from 16 to 48. The performance increase comes from the tweaks to the core plus the slightly higher clock speed but in games that will make heavy use of shaders* the X1900XT will have the advantage at being able to process them faster.

You can find a decent database at this link that will allow you to compare the underlying hardware.

*The fancy effects you see in modern games and pretty much all future games.

It is a complicated subject to talk about as both vendors have different ways of going about it at a different price points for example at the high end NVIDIA take a more "balanced" view by increasing the numbers of texture units and pixel shaders. In the mid-range NVIDIA's 7600GT and ATI's X1600XT both have the same number of pixel shaders (12) but NVIDIA has a higher clock speed plus more texture units (12) compared to ATI's (4), this helps the 7600GT stomp all over the X1600 parts.

awhir

8T8 wrote:

Just to further expand on that the difference between X1900XT and the X1800XT is that the X1900XT and XTX is a refinement of the X1800XT core.

It has been shrunk to improve manufacturing yields and clock speeds but they also upped the number of pixel shaders from 16 to 48. The performance increase comes from the tweaks to the core plus the slightly higher clock speed but in games that will make heavy use of shaders* the X1900XT will have the advantage at being able to process them faster.

You can find a decent database at this link that will allow you to compare the underlying hardware.

*The fancy effects you see in modern games and pretty much all future games.

It is a complicated subject to talk about as both vendors have different ways of going about it at a different price points for example at the high end NVIDIA take a more "balanced" view by increasing the numbers of texture units and pixel shaders. In the mid-range NVIDIA's 7600GT and ATI's X1600XT both have the same number of pixel shaders (12) but NVIDIA has a higher clock speed plus more texture units (12) compared to ATI's (4), this helps the 7600GT stomp all over the X1600 parts.

thank you