In Part 1 of this series, we saw newer AMD Catalyst drivers slowing down the Radeon HD4000, HD5000 and HD6000 graphics cards under Windows XP. This time, we will look at how the Radeon HD7970 with the newer GCN architecture is affected by this problem.

I will run the same tests on the same system as used in the previous part of this series. A Core2 Duo E7300 on a Gigabyte 965P motherboard with 4GB DDR2-800 memory, using Windows XP SP3. But this time, I will test the Radeon HD7970 – the most powerful AMD graphics card that has drivers for Windows XP. In addition, the card is using a newer and radically different architecture than the previous cards. The previous VLIW5 or VLIW4 architectures relied on the shader compiler to achieve optimal utilization of execution units, and even then it was not always possible to schedule the instructions in such a way that would use all the execution units available at any given time. Then with the HD7000 series, AMD switched to the GCN architecture, which uses scalar shader execution units, similar to how Nvidia was designing its cards since the Geforce 8800 series. In theory, this should allow the hardware scheduler to use the available execution units more effectively, relying less on the shader compiler. And maybe, in theory, this will result in a more consistent performance across different driver versions, and less dependence on the CPU? Let’s see if that hypothesis holds up, as we look at the performance of the Radeon 7970 in the table below.

	Catalyst 12.4	Catalyst 13.4	Catalyst 14.4
Crysis	76	76	79
Stalker	68	68	70
Fallout 3	45	20	21
Borderlands	52	52	53
Far Cry 2	61	60	61
Stalker: Clear Sky	94	91	92
Clear Sky bench	52	52	51
Far Cry 2 bench	74	70	69

What do we have here? It appears that there is mostly consistent performance between the various driver versions, with only Fallout 3 dropping to a ridiculously low performance level for no explicable reason, just as we saw with the older graphics cards. But not so fast! Not only did I monitor the framerate in MSI afterburner, I also noted the GPU and CPU utilization in each of the manual game tests. As before, the number typically changes +/- a few percentage points over time, so I recorded the statistical mode of the measurement, or the number that appears most often. Take a look at the GPU usage for each driver in the table below.

	Catalyst 12.4	Catalyst 13.4	Catalyst 14.4
Crysis	63	66	66
Stalker	43	93	92
Fallout 3	36	99	99
Borderlands	67	87	88
Far Cry 2	40	74	74
Stalker: Clear Sky	46	94	96

In both Catalyst 13.4 and 14.4 we see a much higher GPU utilization compared to the older Catalyst 12.4 driver, even thought performance is not changed much in most games. Talk about efficient use of execution units, heh! The low GPU utilization in the older driver is most likely caused by CPU bottlenecking, so no surprises there. But why the much higher utilization in the newer drivers if performance does not go up? What in the world is the Radeon 7970 doing at 99% utilization in Fallout 3 and only having a miserly 20fps to show for it, where before it was lazily skipping along at 36% utilization and 45fps? Mining cryptocurrency? (I kid, but it’s funny until it’s not). This also brings up the possibility that on a faster system with a much more powerful processor, the performance will noticeably go down from the newer drivers, because you will not be CPU limited with the Catalyst 12.4 driver. And what about the earlier graphics cards? Did the GPU utilization also increase from the newer driver while actual performance decreased? Yes it did. I will not throw up any more tables here, but with the Radeon 6950, Catalyst 11.5 and 12.4 had noticeably lower GPU utilization than Catalyst 13.4 and 14.4, while also having better performance.

Overall, this test leaves me with more questions than answers. Will a newer, much faster processor expose the newer drivers lowering performance of the Radeon 7970 just as we saw with older graphics cards? Or will it unlock some hidden performance enhancements in the newer drivers and finally make sense of it all? Stay tuned to find out.

Related Content

Go back to Part 1 – AMD Catalyst Drivers for Windows XP: Newer is NOT Better
Go on to Part 3 – AMD Catalyst and Windows XP: Unleashing performance with Intel Sandy Bridge