AMD ATI Comparison Table

With more and more graphics chips being released every day it became very complicated for the user who does not follow the video card market to know the differences among all ATI graphic chips in the market today. To facilitate knowing and understanding the difference among major ATI chips, we have compiled the following table.

It is important to notice that starting 2007 both ATI and nVidia started referring to the memory clock of their video cards with the real clock rate used. In the past manufacturers referred the memory clocks with double their real clock rate, because DDR and subsequent technologies (DDR2, GDDR3, etc) allow the memory chip to transfer two data per clock cycle. So a video card with a memory chip running at 500 MHz would be referred as having a 1 GHz memory. In order to keep the compatibility of our table, we are still referring the memory clocks with the DDR naming convention – i.e. double the real clock rate – on cards with memories based on DDR or subsequent technologies.

Chip	Core Clock	Memory Clock	Memory Interface	Memory Transfer Rate	Pixels per clock	DirectX
Radeon 9200	250 MHz	400 MHz	128-bit	6.4 GB/s	4	8.1
Radeon 9200 Pro	275 MHz	550 MHz	128-bit	8.8 GB/s	4	8.1
Radeon 9200 SE	200 MHz	333 MHz	64-bit	2.6 GB/s	4	8.1
Radeon 9250	240 MHz	400 MHz	128-bit	6.4 GB/s	4	8.1
Radeon 9250 SE	240 MHz	400 MHz	64-bit	3.2 GB/s	4	8.1
Radeon 9500	275 MHz	540 MHz	128-bit	8.6 GB/s	4	9.0
Radeon 9550	250 MHz	400 MHz	128-bit	6.4 GB/s	4	9.0
Radeon 9550 SE	250 MHz	400 MHz	64-bit	3.2 GB/s	4	9.0
Radeon 9500 Pro	275 MHz	540 MHz	128-bit	8.6 GB/s	8	9.0
Radeon 9600	325 MHz	400 MHz	128-bit	6.4 GB/s	4	9.0
Radeon 9600 Pro	400 MHz	600 MHz	128-bit	9.6 GB/s	4	9.0
Radeon 9600 SE	325 MHz	400 MHz	64-bit	3.2 GB/s	4	9.0
Radeon 9600 XT	500 MHz	600 MHz	128-bit	9.6 GB/s	4	9.0
Radeon 9700	275 MHz	540 MHz	256-bit	17.2 GB/s	8	9.0
Radeon 9700 Pro	325 MHz	620 MHz	256-bit	19.8 GB/s	8	9.0
Radeon 9800	325 MHz	580 MHz	256-bit	18.56 GB/s	8	9.0
Radeon 9800 Pro	380 MHz	680 MHz	256-bit	21.7 GB/s	8	9.0
Radeon 9800 SE	325 MHz	500 MHz	128-bit or 256-bit	8 GB/s or 16 GB/s	4	9.0
Radeon 9800 XT	412 MHz	730 MHz	256-bit	23.3 GB/s	8	9.0
Radeon X300 SE	325 MHz	400 MHz	64-bit	3.2 GB/s	4	9.0
Radeon X300	325 MHz	400 MHz	128-bit	6.4 GB/s	4	9.0
Radeon X550	400 MHz	500 MHz	128-bit or 64-bit	8 GB/s or 4 GB/s	4	9.0
Radeon X600 Pro	400 MHz	600 MHz	128-bit	9.6 GB/s	4	9.0
Radeon X600 XT	500 MHz	730 MHz	128-bit	11.68 GB/s	4	9.0
Radeon X700	400 MHz	600 MHz	128-bit	9.6 GB/s	8	9.0
Radeon X700 Pro	420 MHz	864 MHz	128-bit	13.8 GB/s	8	9.0
Radeon X700 XT	475 MHz	1.05 GHz	128-bit	16.8 GB/s	8	9.0
Radeon X800 SE	*	*	*	*	8	9.0
Radeon X800	400 MHz	700 MHz	256-bit	22.4 GB/s	12	9.0
Radeon X800 XL	400 MHz	1 GHz	256-bit	32 GB/s	16	9.0
Radeon X800 GT	475 MHz	**	128-bit or 256-bit	**	8	9.0
Radeon X800 GTO	400 MHz	1 GHz ***	256-bit	32 GB/s	12	9.0
Radeon X800 Pro	475 MHz	950 MHz	256-bit	30.4 GB/s	12	9.0
Radeon X800 XT	500 MHz	1 GHz	256-bit	32 GB/s	16	9.0
Radeon X800 XT PE	520 MHz	1.12 GHz	256-bit	35.8 GB/s	16	9.0
Radeon X850 Pro	520 MHz	1.08 GHz	256-bit	34.56 GB/s	12	9.0
Radeon X850 XT	520 MHz	1.08 GHz	256-bit	34.56 GB/s	16	9.0
Radeon X850 PE	540 MHz	1.18 GHz	256-bit	37.76 GB/s	16	9.0
Radeon X1050	****	****	****	****	4	9.0c
Radeon X1300 HM	450 MHz	1 GHz	128-bit or 64-bit or 32-bit	16 GB/s or 8 GB/s or 4 GB/s	4	9.0c
Radeon X1300	450 MHz	500 MHz	128-bit or 64-bit or 32-bit	8 GB/s or 4 GB/s or 2 GB/s	4	9.0c
Radeon X1300 Pro	600 MHz	800 MHz	128-bit or 64-bit or 32-bit	12.8 GB/s or 6.4 GB/s or 3.2 GB/s	4	9.0c
Radeon X1300 XT	500 MHz	800 MHz (DDR2) or 1 GHz (GDDR3)	128-bit	12.8 GB/s or 16 GB/s	12	9.0c
Radeon X1550	450 MHz or 550 MHz or 600 MHz	800 MHz	64-bit or 128-bit	6.4 GB/s or 12.8 GB/s	4	9.0c
Radeon X1600 Pro	500 MHz or 575 MHz	780 MHz	128-bit	12.48 GB/s	12	9.0c
Radeon X1600 XT	590 MHz	1.38 GHz	128-bit	22.08 GB/s	12	9.0c
Radeon X1650 Pro	600 MHz	1.40 GHz	128-bit	22.40 GB/s	12	9.0c
Radeon X1650 XT	575 MHz	1.35 GHz	128-bit	21.60 GB/s	24	9.0c
Radeon X1800 GTO	500 MHz	1 GHz	256-bit	32 GB/s	12	9.0c
Radeon X1800 XL	500 MHz	1 GHz	256-bit	32 GB/s	16	9.0c
Radeon X1800 XT	625 MHz	1.5 GHz	256-bit	48 GB/s	16	9.0c
Radeon X1900 GT	575 MHz	1.2 GHz	256-bit	38.4 GB/s	36	9.0c
Radeon X1900 XT	625 MHz	1.45 GHz	256-bit	46.4 GB/s	48	9.0c
Radeon X1900 XTX	650 MHz	1.55 GHz	256-bit	49.6 GB/s	48	9.0c
Radeon X1950 GT	500 MHz	1.2 GHz	256-bit	38.4 GB/s	36	9.0c
Radeon X1950 Pro	575 MHz	1.38 GHz	256-bit	44.16 GB/s	36	9.0c
Radeon X1950 XT	625 MHz	1.8 GHz	256-bit	57.6 GB/s	48	9.0c
Radeon X1950 XTX	650 MHz	2 GHz	256-bit	64 GB/s	48	9.0c
Radeon HD 2400 Pro	525 MHz	800 MHz	64-bit	6.4 GB/s	40 *****	10
Radeon HD 2400 XT	700 MHz	1.6 GHz	64-bit	12.8 GB/s	40 *****	10
Radeon HD 2600 Pro	600 MHz	800 MHz	128-bit	12.8 GB/s	120 *****	10
Radeon HD 2600 XT	800 MHz	1.6 GHz (GDDR3) or 2.2 GHz (GDDR4)	128-bit	25.6 GB/s (GDDR3) or 35.2 GB/s (GDDR4)	120 *****	10
Radeon HD 2900 GT	600 MHz	1.6 GHz	256-bit	51.2 GB/s	240 *****	10
Radeon HD 2900 Pro	600 MHz	1.85 GHz	512-bit	118.4 GB/s	320 *****	10
Radeon HD 2900 XT	740 MHz	1.65 GHz (GDDR3) or 2 GHz (GDDR4)	512-bit	105.6 GB/s (GDDR3) or 128 GB/s (GDDR4)	320 *****	10
Radeon HD 3450 ^	600 MHz	1 GHz	64-bit	8 GB/s	40 *****	10.1
Radeon HD 3470 ^	800 MHz	1.90 GHz	64-bit	15.2 GB/s	40 *****	10.1
Radeon HD 3650 ^	725 MHz	1 GHZ (DDR2) or 1.6 GHz (GDDR3)	128-bit	16 GB/s (DDR2) or 25.6 GB/s (GDDR3)	120 *****	10.1
Radeon HD 3690 ^	668 MHz	1,656 MHz	128-bit	26.5 GB/s	120 *****	10.1
Radeon HD 3850 ^	670 MHz	1.66 GHz	256-bit	53.12 GB/s	320 *****	10.1
Radeon HD 3870 ^	775 MHz	2.25 GHz	256-bit	72 GB/s	320 *****	10.1
Radeon HD 3870 X2 ^  +	825 MHz	1.8 GHz	256-bit	57.6 GB/s	320 *****	10.1
Radeon HD 4350 ^	600 MHz	1 GHz	64-bit	8 GB/s	80 *****	10.1
Radeon HD 4550 ^	800 MHz	1.6 GHz	64-bit	12.8 GB/s	80 *****	10.1
Radeon HD 4650 ^	600 MHz	1 GHz or 1.4 GHz	128-bit	16 GB/s or 22.4 GB/s	320 *****	10.1
Radeon HD 4670 ^	750 MHz	2 GHz (512 MB) or 1,746 MHz (1 GB)	128-bit	32 GB/s or 27.94 GB/s	320 *****	10.1
Radeon HD 4830 ^	575 MHz	1.8 GHz	256-bit	57.6 GB/s	640 *****	10.1
Radeon HD 4850 ^	625 MHz	2 GHz	256-bit	64 GB/s	800 *****	10.1
Radeon HD 4850 X2 ^ +	625 MHz	2 GHz	256-bit	64 GB/s	800 *****	10.1
Radeon HD 4870 ^	750 MHz	3.6 GHz	256-bit	115.2 GB/s	800 *****	10.1
Radeon HD 4870 X2 ^ +	750 MHz	2.6 GHz	256-bit	115.2 GB/s	800 *****	10.1

* ATI doesn’t set a default clock for Radeon X800 SE chip. The specs depend on the video card manufacturer. So you have to take care when comparing video cards using this chip.

** Depends on the model. There are boards based on Radeon X800 GT using DDR, DDR2 and GDDR3 memories running at different speeds. We’ve seen GDDR3 models running at 980 MHz and DDR models running at 700 MHz. You can calculate the memory transfer rate using the formula memory clock x number of bits / 8. A model with GDDR3 memory running at 980 MHz and 256-bit interface has a transfer rate of 31.36 GB/s.

*** There are models using DDR memories and running at lower clock rates.

**** There are three video card versions using this chip with very different specs, depending on the memory chips used. If they are 128 MB DDR, then the graphics chip runs at 400 MHz, the memory runs at 500 MHz, a 128-bit memory interface is used and the memory has a maximum theoretical transfer rate of 8 GB/s. If the card has 128 MB DDR2, then the graphics chip runs at 325 MHz, the memory runs at 666 MHz, a 64-bit memory interface is used and the memory has a maximum theoretical transfer rate of 5.3 GB/s. And finally if the card has 256 MB DDR2 then the graphics chip runs at 400 MHz, the memory runs at 666 MHz, a 128-bit memory interface us used and the memory has a maximum theoretical transfer rate of 10.6 GB/s.

***** The shader unit is unified, meaning that this chip doesn’t have separated pixel shader and vertex shader units. On video cards from Radeon HD 2400 and HD 2600 series the video card manufacturer can use a different clock for the memory (usually lower, thus achieveing a lower performance compared to the reference model); the clock rates published here are the official one.

^ Based on PCI Express 2.0, which doubles the available I/O bandwidth from 2.5 GB/s to 5 GB/s if a PCI Express 2.0 motherboard is used.

+ Radeon HD 3870 X2, Radeon HD 4850 X2 and HD 4870 X2 use two Radeon chips working in parallel (CrossFire). The specs published are for only one of the chips.

When you compare chips, you have to be very careful. Judging from the table, a Radeon 9800 may seem slower than a Radeon 9600 Pro, since its clock is inferior, and a Radeon X700 Pro seems faster than a Radeon X800 since it uses a higher clock rate.

However, Radeon 9800 accesses its memory using a 256-bit interface and processes eight pixels per clock pulse, while the Radeon 9600 Pro accesses its memory using a 128-bit interface and processes four pixels per clock pulse. This means that memory access and processing performance of the Radeon 9800 would the double of that of the Radeon 9600 Pro if they were working at the same clock. In other words, a Radeon 9600 Pro would have work at 650 MHz and access the memory at 1.360 MHz to have the same performance of the Radeon 9800.

The same idea goes for the Radeon X700 Pro example, it accesses memory using a 128-bit interface and processes data at 8 pixels per clock tick, while Radeon X800 accesses memory using a 256-bit interface and processes data at 12 pixels per clock tick.

Therefore, it is not correct to compare graphic chips only through their clocks. For the processing performance you will have to compare the clocks and the number of pixels per clock. As of the memory, the right way to compare its performance among different chips is through their memory transfer rate, which is calculated using the formula (clock x bits per clock)/ 8.

As you can see in the table, “SE” chips are the simplest and access the memory at only 64 bits per time. Another detail is that ATI uses the letters “XT” to indicate the fastest chip in a series, while its competitor, nVidia, uses the same letters to indicate the simplest chip in a series.

“PE” stands for “Platinum Edition” and are models even faster than the “XT” models, aimed to gamers with money.

As for the DirectX version, check the table below:

DirectX	Shader Model
7.0	No
8.1	1.4
9.0	2.0
9.0c	3.0
10	4.0
10.1	4.1

Nvidia Chips Comparison

Chip	Core Clock	Memory Clock	Memory Interface	Memory Transfer Rate	Pixels per clock	DirectX
GeForce 4 MX 440 AGP 8x	275 MHz	512 MHz	128-bit	8.1 GB/s	2	7
GeForce MX 4000	250 MHz	*	32-bit or 64-bit or 128-bit	*	2	7
GeForce FX 5200	250 MHz	400 MHz	64-bit or 128-bit	3.2 GB/s or 6.4 GB/s	4	9.0
GeForce FX 5200 Ultra	350 MHz	650 MHz	128-bit	10.4 GB/s	4	9.0
GeForce FX 5600	325 MHz	550 MHz	128-bit	8.8 GB/s	4	9.0
GeForce FX 5500	270 MHz	400 MHz	64-bit or 128-bit	3.2 GB/s or 6.4 GB/s	4	9.0
GeForce FX 5600 Ultra	500 MHz	800 MHz	128-bit	12.8 GB/s	4	9.0
GeForce FX 5700 LE	250 MHz	400 MHz	128-bit	6.4 GB/s	4	9.0
GeForce FX 5700	425 MHz	600 MHz	128-bit	9,6 GB/s	4	9.0
GeForce FX 5700 Ultra	475 MHz	900 MHz	128-bit	14.4 GB/s	4	9.0
GeForce FX 5800	400 MHz	900 MHz	128-bit	14.4 GB/s	8	9.0
GeForce FX 5800 Ultra	500 MHz	1 GHz	128-bit	16 GB/s	8	9.0
GeForce FX 5900 XT	390 MHz	680 MHz	256-bit	21.7 GB/s	8	9.0
GeForce FX 5900	400 MHz	850 MHz	256-bit	27.2 GB/s	8	9.0
GeForce FX 5900 Ultra	450 MHz	850 MHz	256-bit	27.2 GB/s	8	9.0
GeForce FX 5950 Ultra	475 MHz	950 MHz	256-bit	30.4 GB/s	8	9.0
GeForce PCX 5300	325 MHz	650 MHz	128-bit	10.4 GB/s	4	9.0
GeForce PCX 5750	475 MHz	900 MHz	128-bit	14.4 GB/s	4	9.0
GeForce PCX 5900	350 MHz	500 MHz	256-bit	17.6 GB/s	8	9.0
GeForce PCX 5950	475 MHz	900 MHz	256-bit	30.4 GB/s	8	9.0
GeForce 6200	300 MHz	550 MHz	128-bit	8.8 GB/s	4	9.0c
GeForce 6200 LE	350 MHz	550 MHz	64-bit	4.4 GB/s	2	9.0c
GeForce 6200 (TC)	350 MHz	666 MHz *	32-bit or 64-bit	2.66 GB/s or 5.32 GB/s *	4	9.0c
GeForce 6500 (TC)	400 MHz	666 MHz *	32-bit or 64-bit	2.66 GB/s or 5.32 GB/s *	4	9.0c
GeForce 6600	300 MHz	550 MHz *	64-bit or 128-bit	4.4 GB/s or 8.8 GB/s *	8	9.0c
GeForce 6600 DDR2	350 MHz	800 MHz *	128-bit	12.8 GB/s *	8	9.0c
GeForce 6600 LE	300 MHz	*	64-bit or 128-bit	*	4	9.0c
GeForce 6600 GT	500 MHz	1 GHz	128-bit	16 GB/s	8	9.0c
GeForce 6600 GT AGP	500 MHz	900 MHz	128-bit	14.4 GB/s	8	9.0c
GeForce 6800 LE	300 MHz	700 MHz	256-bit	22.4 GB/s	8	9.0c
GeForce 6800 XT	325 MHz	600 MHz	256 bits	19.2 GB/s	8	9.0c
GeForce 6800 XT AGP	325 MHz	700 MHz	256 bits	22.4 GB/s	8	9.0c
GeForce 6800	325 MHz	600 MHz	256-bit	19.2 GB/s	12	9.0c
GeForce 6800 AGP	325 MHz	700 MHz	256-bit	22.4 GB/s	12	9.0c
GeForce 6800 GS	425 MHz	1 GHz	256-bit	32 GB/s	12	9.0c
GeForce 6800 GS AGP	350 MHz	1 GHz	256-bit	32 GB/s	12	9.0c
GeForce 6800 GT	350 MHz	1 GHz	256-bit	32 GB/s	16	9.0c
GeForce 6800 Ultra	400 MHz	1.1 GHz	256-bit	35.2 GB/s	16	9.0c
GeForce 6800 Ultra Extreme	450 MHz	1.1 GHz	256-bit	35.2 GB/s	16	9.0c
GeForce 7100 GS (TC)	350 MHz	666 MHz *	64-bit	5.3 GB/s *	4	9.0c
GeForce 7200 GS (TC)	450 MHz	800 MHz *	64-bit	6.4 GB/s *	4	9.0c
GeForce 7300 SE (TC)	225 MHz	*	64-bit	*	4	9.0c
GeForce 7300 LE (TC)	450 MHz	648 MHz *	64-bit	5.2 GB/s *	4	9.0c
GeForce 7300 GS (TC)	550 MHz	810 MHz *	64-bit	6.5 GB/s *	4	9.0c
GeForce 7300 GT (TC)	350 MHz	667 MHz	128-bit	10.6 GB/s	8	9.0c
GeForce 7600 GS	400 MHz	800 MHz	128-bit	12.8 GB/s	12	9.0c
GeForce 7600 GT	560 MHz	1.4 GHz	128-bit	22.4 GB/s	12	9.0c
GeForce 7800 GS	375 MHz	1.2 GHz	256-bit	38.4 GB/s	16	9.0c
GeForce 7800 GT	400 MHz	1 GHz	256-bit	32 GB/s	20	9.0c
GeForce 7800 GTX	430 MHz	1.2 GHz	256-bit	38.4 GB/s	24	9.0c
GeForce 7800 GTX 512	550 MHz	1.7 GHz	256-bit	54.4 GB/s	24	9.0c
GeForce 7900 GS	450 MHz	1.32 GHz	256-bit	42.2 GB/s	20	9.0c
GeForce 7900 GT	450 MHz	1.32 GHz	256-bit	42.2 GB/s	24	9.0c
GeForce 7900 GTX	650 MHz	1.6 GHz	256-bit	51.2 GB/s	24	9.0c
GeForce 7950 GT	550 MHz	1.4 GHz	256-bit	44.8 GB/s	24	9.0c
GeForce 7950 GX2 **	500 MHz	1.2 GHz	256-bit	38.4 GB/s	24	9.0c
GeForce 8400 GS ***	450 MHz / 900 MHz	800 MHz	64-bit	6.4 GB/s	16	10
GeForce 8500 GT ***	450 MHz / 900 MHz	666 MHz or 800 MHz	128-bit	10.6 GB/s or 12.8 GB/s	16	10
GeForce 8600 GT DDR2 ***	540 MHz / 1.18 GHz	666 MHz or 800 MHz	128-bit	10.6 GB/s or 12.8 GB/s	32	10
GeForce 8600 GT GDDR3 ***	540 MHz / 1.18 GHz	1.4 GHz	128-bit	22.4 GB/s	32	10
GeForce 8600 GTS ***	675 MHz / 1.45 GHz	2 GHz	128-bit	32 GB/s	32	10
GeForce 8800 GS *** ^	550 MHz / 1,375 MHz	1.6 GHz	192-bit	38.4 GB/s	96	10
GeForce 8800 GT *** ^	600 MHz / 1.5 GHz	1.8 GHz	256-bit	57.6 GB/s	112	10
GeForce 8800 GTS ***	500 MHz / 1.2 GHz	1.6 GHz	320-bit	64 GB/s	96	10
GeForce 8800 GTS 512 *** ^	650 MHz / 1,625 MHz	1.94 GHz	256-bit	62.08 GB/s	128	10
GeForce 8800 GTX ***	575 MHz / 1.35 GHz	1.8 GHz	384-bit	86.4 GB/s	128	10
GeForce 8800 Ultra ***	612 MHz / 1.5 GHz	2.16 GHz	384-bit	103.6 GB/s	128	10
GeForce 9400 GT *** ^	550 MHz / 1.4 GHz	800 MHz	128-bit	12.8 GB/s	16	10
GeForce 9500 GT *** ^	550 MHz / 1.4 GHz	1 GHz (DDR2) or 1.6 GHz (GDDR3)	128-bit	16 GB/s (DDR2) or 25.6 GB/s (GDDR3)	32	10
GeForce 9600 GSO *** ^	550 MHz / 1.35 GHz	1.6 GHz	192-bit	38.4 GB/s	96	10
GeForce 9600 GT *** ^	650 MHz / 1,625 MHz	1.8 GHz	256-bit	57.6 GB/s	64	10
GeForce 9800 GT *** ^	600 MHz / 1.5 GHz	1.8 GHz	256-bit	57.6 GB/s	112	10
GeForce 9800 GTX *** ^	675 MHz / 1,688 MHz	2.2 GHz	256-bit	70.4 GB/s	128	10
GeForce 9800 GTX+ *** ^	738 MHz / 1,836 MHz	2.2 GHz	256-bit	70.4 GB/s	128	10
GeForce 9800 GX2 ** *** ^	600 MHz / 1.5 GHz	2 GHz	256-bit	64 GB/s	128	10
GeForce GTX 260 *** ^	576 MHz / 1,242 MHz	2 GHz	448-bit	112 GB/s	192	10
GeForce GTX 280 *** ^	602 MHz / 1,296 MHz	2.21 GHz	512-bit	141.7 GB/s	240	10

* The manufacturer can setup a different memory clock rate or interface, so pay attention because not all video cards based on this chip have this spec. The memory transfer rate will depend on the interface and clock rate used. See how to calculate below.

** GeForce 7950 GX2 and GeForce 9800 GX2 use two graphics processors in parallel (SLI mode). The specs published are for just one of the chips.

*** GeForce 8, 9 and 200 series use two clocks, the higher one is used by the shader unit and the lower one by the rest of the chip. The shader unit is unified, meaning that these chips don’t have separated pixel shader and vertex shader units.

^ Based on PCI Express 2.0, which doubles the available I/O bandwidth from 2.5 GB/s to 5 GB/s if a PCI Express 2.0 motherboard is used.

(TC) means TurboCache. TurboCache is a technology that allows the video card to simulate more video memory by using part of the main system RAM as video memory.

At first nVidia’s profusion of letters may seem confusing. The GeForce FX 5700 Ultra chip works at a higher clock than the GeForce FX 5900, GeForce FX 5900 Ultra and GeForce FX 5900 XT chips, and this may make you think that a GeForce FX 5700 Ultra is the faster than chips in the 5900 series.

But that is not really so. Chips from the GeForce FX 5900 series access the memory at 256 bits per time, while the memory is accessed at 128 bits in the FX 5700 series. That makes the 5900 series memory access performance twice as fast as those of the previous series. For instance, the GeForce FX 5700 Ultra would have to access its memory at 1,700 MHz – the double of the memory clock used – to reach the memory performance of the GeForce FX 5900 Ultra.

Another example. From the table you may think GeForce 6600 GT is faster than a GeForce 6800 because it has a higher clock rate (500 MHz against 325 MHz). But GeForce 6800 accesses memory 256 bits at a time while GeForce 6600 GT accesses memory 128 bits at a time, and also GeForce 6800 processes 12 pixels per clock tick, while GeForce 6600 GT processes eight pixels per clock.

The right way to compare the memory performance of different chips is through their memory transfer rate, which is calculated using the formula (clock x bits per clock ) / 8.

Another difference is the graphic processor of the FX 5900 series, which processes eight pixels per clock pulse, while the graphic chip only processes four pixels per clock in the other series. In other words, despite having a higher clock, the graphic processing performance of the GeForce FX 5700 Ultra is inferior than those of chips from the FX 5900 series, as they process the double of pixels when work at the same clock (simply put, the GeForce FX 5700 Ultra would have to work at twice its clock to have the same performance of the GeForce FX 5900 Ultra).

Therefore, it is not correct to compare graphic chips only through their clocks.

We must be careful with the GeForce FX 5900 XT, too. While ATI uses the letters “XT” to indicate high-end chips (for ex.: Radeon 9800 XT), nVidia uses the same letters to indicate the low-end chips of the series (see table).

You have to be very carefull with low-end video cards using nVidia chips, because they can use different clock rates and different memory interface from the table. For example, you can find GeForce FX 5200, GeForce FX 5500 and GeForce 6600 with 64-bit or 128-bit interface. We’ve seen GeForce FX 5200, GeForce FX 5500 and GeForce 6200 with 32-bit interface on the market!