Doom 3	Source: id Software

Doom 3 is the most advanced OpenGL game to date. It takes advantage of the latest videocard technology and pushes the processing power of the CPU to its absolute limits. At its highest setting, Ultra quality, texture sizes pass the 500MB mark which means even tomorrow's videocards will have a hard time running everything. The frame rates in the game itself are locked at 60 fps so anything above that point is wasted. Each test is run three times and with the third run being recorded.

Doom3
HQ 1024x768	FPS	Ranking
MSI RX1800XT-VT2D512E	123.7
Gigabyte GV-RX18L256V-B	112.1
ATi Radeon X850 XT PE	116.9
MSI RX850XT-TD256E	112.5
MSI RX800XT-VTD256E	109
ATi Radeon X800 XL	101.8
PowerColor X700 Pro	54.3
MSI NX7800GTX-VT2D512E	123.6
MSI NX7800GTX-VT2D256E (Single)	123.5
Asus EN7800GT 2DHTV/256M/OSP/A (Single)	125.3
MSI NX6800GT-T2D256E	112.6
MSI NX6800-TD128E (Single)	87.8
MSI NX6600GT-TD128E (Single)	92.4
Albatron GeForce 6600-512	53
Albatron GeForce 6600-512 (490/550)	64.8
HQ1600x1200	FPS	Ranking
MSI RX1800XT-VT2D512E	84
Gigabyte GV-RX18L256V-B	63.6
ATi Radeon X850 XT PE	66
MSI RX850XT-TD256E	61.8
MSI RX800XT-VTD256E	58.4
ATi Radeon X800 XL	52.5
PowerColor X700 Pro	25.9
MSI NX7800GTX-VT2D512E	106.1
MSI NX7800GTX-VT2D256E (Single)	97.6
Asus EN7800GT 2DHTV/256M/OSP/A (Single)	87.2
MSI NX6800GT-T2D256E	70.4
MSI NX6800-TD128E (Single)	46.3
MSI NX6600GT-TD128E (Single)	47.4
Albatron GeForce 6600-512	26.2
Albatron GeForce 6600-512 (490/550)	32.4
UQ 1024x768	FPS	Ranking
MSI RX1800XT-VT2D512E	122.7
Gigabyte GV-RX18L256V-B	102.4
ATi Radeon X850 XT PE	113.1
MSI RX850XT-TD256E	108.3
MSI RX800XT-VTD256E	104.5
ATi Radeon X800 XL	97.8
PowerColor X700 Pro	52.8
MSI NX7800GTX-VT2D512E	125.4
MSI NX7800GTX-VT2D256E (Single)	122
Asus EN7800GT 2DHTV/256M/OSP/A (Single)	121.2
MSI NX6800GT-T2D256E	111
MSI NX6800-TD128E (Single)	88.4
MSI NX6600GT-TD128E (Single)	87.5
Albatron GeForce 6600-512	49.6
Albatron GeForce 6600-512 (490/550)	59.5
UQ 1600x1200	FPS	Ranking
MSI RX1800XT-VT2D512E	82.6
Gigabyte GV-RX18L256V-B	58.8
ATi Radeon X850 XT PE	63.8
MSI RX850XT-TD256E	59.5
MSI RX800XT-VTD256E	56.2
ATi Radeon X800 XL	51
PowerColor X700 Pro	21.9
MSI NX7800GTX-VT2D512E	106.7
MSI NX7800GTX-VT2D256E (Single)	96.7
Asus EN7800GT 2DHTV/256M/OSP/A (Single)	84.2
MSI NX6800GT-T2D256E	69.3
MSI NX6800-TD128E (Single)	48.7
MSI NX6600GT-TD128E (Single)	46
Albatron GeForce 6600-512	25.1
Albatron GeForce 6600-512 (490/550)	30.6

Doom 3 results are good at 1024x768, even in Ultra Quality mode. It just goes to show that the extra memory can beneficial.