AMD Radeon HD 6450 Review: Caicos Cometh

AMD populates the entry-level tier with its new Radeon HD 6450, based on the Caicos graphics processor. Does this board have what it takes to stand out in the crowded low-end market and vie for a spot in your next home theater PC?

Hot on the heels of the Radeon HD 6790, AMD is releasing another new graphics card. This time the target is the sub-£50 price range, bringing Radeon 6000-series features to the entry-level market. Meet the Radeon HD 6450.

Low-end graphics cards account for the bulk of sales, and that means competition: the Radeon HD 5450, Radeon HD 5550, GeForce GT 220 and GeForce GT 430 are only a few of the models that folks will consider as alternatives. Before we compare them, let’s see what the new ‘Caicos’ GPU has to offer:

The Radeon HD 6450’s ‘Caicos’ GPU is based on the same architecture that we first saw in the Radeon HD 6800 series’ ‘Barts’ graphics processor. The new model is far less ambitious, with only 1/7^th of the Radeon HD 6870’s vital statistics. Instead of 14 SIMD engines, the Caicos has two, each containing four texture units and 16 stream processors. With 5 ALU’s per stream processor, the resulting total is 160. These are coupled to a single render back-end with four colour ROPs, attached to a lone 64-bit memory controller.

It’s as though AMD paid close attention to our Radeon HD 5450 review in February of 2010, where we said: “It is unfortunate that that the SIMD engines have been cut in half compared to the GPUs found on… …higher models that sport a more robust 16 stream processors per.” Because each of ‘Caicos’ SIMDs sports the same specifications as the ones in ‘Barts’, we can expect a sizable performance gain over the Radeon HD 5450.

But that’s not the only improvement. The Radeon HD 6450 comes in two flavours: DDR3 and GDDR5. Since GDDR5 memory doubles the bandwidth vs. DDR3, this option should compensate for the restrictive 64-bit memory interface.

Finally, like all products in the Radeon HD 6000 family, this latest model boasts improved tessellation performance, Eyefinity enhancements, and of course UVD 3 including the ability to accelerate Blu-ray 3D video over HDMI 1.4a.

Now that we have a good idea how powerful the Radeon HD 6450 should be, let’s take a closer look at the playing field:

We can see a clear lineage between the Radeon HD 6450 and Radeon HD 5450, with only the number of stream processors doubled. This in itself should provide a huge performance advantage though, and when equipped with GDDR5 the new card should excel in the gaming arena.

The Radeon HD 5550 is far more interesting competition.  It essentially doubles all of the Radeon HD 6450’s statistics: 320 shader processors, 16 texture units, and 8 ROPs over a 128-bit memory interface. While the GDDR5 version of the new card might be able to keep up when it comes to memory bandwidth, the higher core clock doesn’t compensate for the ‘Caicos’ hardware deficit. Of course, the Radeon HD 5550 doesn’t support Blu-ray 3D decode acceleration--although it is capable of playing back this format over HDMI 1.4a, the bulk of the work is left to the CPU.

The GeForce GT 220 DDR2 is also priced similarly to the Radeon HD 6450 GDDR5, and while it sports a powerful GPU and a 128-bit memory interface it is crippled by slower DDR2 memory. Ironically, despite Nvidia’s lead in the 3D arena this card is not capable of playing back Blu-ray 3D over HDMI—the GeForce GT 430 is Nvidia’s lowest-end card capable of this feat, and it typically costs about £60 (although a couple models can be found for as much as £8 cheaper than that online). Indeed, with twice as many shader cores as the GT 220, the GeForce GT 430 may offer the strongest competition for the 6450 on both the HTPC and gaming fronts.

Let’s have a closer look at the new card before we put it to the test.