Yesterday, Nvidia quietly released three new middle-class GPUs: GeForce GT 630, GeForce GT 640 and GeForce GT 645. Middle-class GPUs are meant for casual or modest gamers that expect to play current games but will turn down settings on the most demanding games.
These three card groups fall in to that category. Lets see if Nvidia did a good job or if we are just faced with renamed old models...
First up is the GeForce GT 630.
1 - GeForce GT 630
Architecture: Kepler GK107
CUDA Cores: 388
Graphics Clock: 875MHz
Memory Clock: 891MHz
Memory: 1GB or 2GB
Memory Interface: DDR3
Memory Interface Width: 128 Bits
Die Size: 28nm
Good: New architecture means – less power consumption, less heating and better performance than its predecessor, GeForce GT 530.
Bad: A 128 bit memory bus will not suffice for large amounts of video memory. It will greatly reduce its performance by becoming a bottleneck for both the 1GB and 2GB versions.
Worse: 2GB will probably be a lot more expensive and it seems like little more than a gimmick as GeForce GT 630 does not seem structured to use the full 2GB of memory and the memory width is not large enough to allow that much data to pass through.
Summary: Despite its bottleneck, GeForce GT 630 ends up being a decent middle-class GPU that will probably be able to play most modern demanding games at high settings but will most likely require some reduced settings for very demanding games, like Metro 2033 and the recently announced Max Payne 3.
Next up is the 3 GeForce GT 640. You should immediately notice that tucked between the newer versions is a GeForce GT 640 built on the older Fermi GF108 architecture. Watch out when buying the GeForce GT 640 as you want to avoid the Fermi GF108. Check out my summary below.
2 - GeForce GT 640
Architecture: Kepler GK107 | Fermi GF116 | Kepler GK107
CUDA Cores: 388 | 144 | 388
Graphics Clock: 797MHz | 720MHz | 950MHz
Memory Clock: 891MHz | 891MHz | 2500MHz
Memory: 1GB or 2GB | 1.5GB or 3GB| 1GB or 2GB
Memory Interface: DDR3 | DDR3 | GDDR5
Memory Interface Width: 128 Bits | 192 Bits | 128 Bits
Die Size: 28nm | 40nm | 28nm
Shader: 5.0 | 5.0 | 5.0
OpenGL: 4.2 | 4.2 | 4.2
DirectX: 11 |11 | 11
For the Kepler GK107 - New architecture means – less power consumption, less heating and obviously better performance.
For the Fermi GF116 – Nothing good here. It’s a renamed GeForce GT 545 DDR3. I wouldn’t want to pick this one by accident instead of one of the other 2. Do your best to check.
For the Kepler GK107 DDR3 - Again, a 128 bit memory bus will not suffice for large amounts of video memory. It will cause a bottleneck for both the 1GB and 2GB versions.
For the Kepler GK107 GDDR5 – Nothing significant to point out.
For the Fermi GF116 – Equipping this version with 1.5GB or 3GB is a waste in the same way as it would be to equip a GeForce GTX 680 with only 256MB. In both cases a lot of the card's performance would remain untapped. The old GeForce GT 545 supported fast GDDR5 and so there was no memory bottleneck but this one is equipped with slower DDR3 causing the 1.5GB and 3GB to never reach their potential due to a large performance bottleneck.
For ALL of them: When you go to a store and buy a new desktop, on the system specifications, the only thing you’ll probably read is “GPU: GeForce GT 640” or if you’re careful “GeForce GT 640 1GB DDR3” so it’s going to be tough knowing if you’re getting a rename, a huge bottleneck, or a very decent fast-middle-class GPU.
In short, remeber that the older architecture GT 640's are offered with either 1.5GB or 3GB. So what you are looking for is the GeForce GT 640 1GB or GeForce GT 640 2GB as these will definitely be the better performing new architecture models. Then choose either the DDR3 for the lesser of the two or the better being GDDR5 models.
For the Kepler GK107 DDR3 1GB or 2GB - Despite its bottleneck, GeForce GT 640 ends up being a decent middle-class GPU that will probably be able to play most modern games at high settings but will most likely require reduced settings for very demanding games like Metro 2033 and Max Payne 3.
For the Kepler GK107 GDDR5 1GB or 2GB – The best choice. GeForce GT 640, equipped with fast GDDR5 and based on the new Kepler Core, results in a pretty solid GPU that will deliver exceptional performance on games using DirectX 11 and will probably handle very demanding games like Metro 2033 and Max Payne 3 at high settings, striking out tesselation, obviously.
For the Fermi GF116 1.5GB or 3GB – The worst choice. Bottlenecked, not as efficient, will heat more and probably be noisier, compared to the new Kepler architecture. Still, probably able to play most modern games at high settings but will most likely require reduced settings for very demanding games like Metro 2033 and Max Payne 3.
Finally we come to the more powerful GPU from our roundup
3 - GeForce GT 645
Architecture: Fermi GF114
CUDA Cores: 288
Graphics Clock: 776MHz
Memory Clock: 891MHz
Memory Interface: GDDR5
Memory Interface Width: 128 Bits
Die Size: 40 nm
Note: Nvidia’s official page says GeForce GT 645 is equipped with a 128 bit bus instead of a 192 bit bus. However, the memory bandwidth they point out is the same as the GeForce GTX 555. Both the memory clock and memory type are the same so either the “128 bit” is a typo or the memory bandwidth of “91.9” was miscalculated. I want to believe in Nvidia but I’ve seen that some of the latest strategic moves have been to reduce the memory "quality", in exchange for increased memory size and so we accept the “128 bit bus” as the correct option.
Good: The GTX 555 is a solid card and so too is the GT 645 but only a good purchase if the price reduces
Bad: Although the GTX 555 is a solid GPU it needs to be mentioned that this feels like a renamed GTX 555 but with a smaller memory bus – 128 bits instead of 192 bits.
Worse: Nothing really bad.
Summary: GeForce GT 645 positions itself in an awkward place. It’s not the GPU enthusiasts want – since it won’t “max” out all games and it’s not the GPU casual gamers want since it probably requires a relatively high budget. The GTX 555 is a good card and therefore so to is the renamed GT 645, but ask yourself if it delivers the right performance to price.
To sum up, the new Kepler GPUs offer better performance and reduced power consumption, while there are some simple renames amongst these cards that seem to lack anything new.
My advice - There are some good cards here so select your budget, define your requirements and pick carefully past possible gimmicks and renames. Rest assured it feels like Nvidia have some good solid choices for the mid-range GPU market.