R9000,在未來的遊戲都會比R8500快許多,而且多餘的錢讓你買高檔的CPU
現在的GPU還沒有primitive processor的功能(NV35, R400)
如果你喜歡玩DX7的遊戲,選擇R8500
如B3d這位仁兄講的
http://www.beyond3d.com/forum/viewtopic.php?t=2465
I didn't say it is bandwidth limited.
One can't even say that - it may be different from game to game.
Even more likely some part of the game-scene is fillrate limited while others might be bandwidth limited.
The biggest bandwidth hog in normal rendering is:
reading the Z-buffer, writing the Z-buffer, writing the color buffer.
Say you have a R9700 non-pro (300/300) just for the ease of calculation.
I assume Z is 8 bit/pixel avg. (because of compression).
Pixel cost (w/o texturing): 8+8+32 bit = 48 bit
Bandwidth available per pixel: 256*2/8 bit = 64 bit
When doing single texturing:
This leaves 64-48 = 16 bit per pixel free.
It's most likely is enough for DXTC but it will be bandwidth limited on uncompressed textures.
When doing 2x texturing:
This leaves 2*64-48 = 80 (2*40) bit per pixel free.
It's more than enough for DXTC even with aniso. It might even be enough with uncompressed textures (w/o aniso) especially if one of them is a low resulotion one. (eg. lightmap)
When doing 3x texturing:
This leaves 3*64-48 = 144 (3*48 ) bit per pixel free.
Not much difference here.
You can see that adding a second TMU will most certainly help 2x texturing but it won't likely be a 2x speed increase, except in special cases.
But let's consider DDRII @ 450 + 2xTMU
When doing single or 2x texturing:
This leaves 96-48 = 48 (2*24) bit per pixel free.
It's quite plenty for 1x texturing. It's likely enough for DXTC even with some aniso. While it's not enough for 32 uncompressed, it might not take a large slowdown in many cases.
When doing 3x or 4x texturing:
This leaves 2*96-48 = 144 (3*48 = 4*36) bit per pixel free.
It will mostly enough for high quality textures as well.
And before someone else points out, I did not calculate with bandwidth efficiency.
這也就是為何R300會贏TI4600的原因,雖然Ti4600跟R300有一樣的材質數
(4X 2= 8x1),但是R300(8管線)有多TI4600(4管線)一倍的渲染效率,所以我覺得花多一點錢在CPU上,花個3千在顯示卡就夠了