Athlon 64 Revision E: Unofficial DDR500 Support

High Speed Dual Core + New Memory Dividers

We’ll start off with the Athlon 64 X2 4800+.

Featuring a 2.4GHz core clock, the 4800+ doesn’t necessarily meet our high clock speed requirement for needing a faster memory bus. Each core also features a 1MB L2 cache, which reduces its dependency on a higher speed memory bus. However, we are dealing with a dual core CPU here - which means that situations where both cores are being used are more likely to increase the chip’s memory bandwidth needs. Because of this, we’ll focus on improvements in multithreaded or multitasking environments, as well as looking at single threaded performance to measure the impact of the faster memory clocks.

According to our table of supported DDR frequencies by the DFI board, the 2.4GHz 4800+ gives us two options above DDR400 - mainly, 218MHz and 240MHz, or an unofficial DDR436 and DDR480, respectively.

Theoretical Memory Bandwidth Comparison

Just to make sure that these new dividers were actually doing something, we used the final 32-bit version of ScienceMark 2.0 to confirm that there were tangible increases in memory bandwidth:

Memory Speed	ScienceMark 2.0 Memory Bandwidth (MB/s)	% Improvement over DDR400
DDR400	5378.08	N/A
DDR436	5495.33	2%
DDR480	5851.52	9%

With DDR436 offering only a 2% increase in peak theoretical memory bandwidth over DDR400, our only hopes for a performance increase are with the much higher bandwidth settings - i.e. DDR480.

Multimedia Content Creation Winstone 2004

Business applications barely made any use of the dual channel memory bus of Socket-939 CPUs, so we had no expectations to see any sort of performance boost from these new DDR speeds in tests like Business Winstone. Thus, we turn to Multimedia Content Creation Winstone 2004, whose Lightwave test is multithreaded and does take advantage of the X2’s dual core setup:

Memory Speed	MMCC Winstone 2004	% Improvement over DDR400
DDR400	41.9	N/A
DDR436	42.3	1%
DDR480	42.7	2%

The biggest performance difference that we see here is 2%, which is less than the 3% variation that we can see between test runs in this particular benchmark.

3D Rendering

3D rendering is another area where we see good use of dual core processors, but these tests also showed us a 0 - 1% increase in performance when comparing DDR480 to DDR400:

Memory Speed	3dsmax 6 - SPECapc Rendering Composite	% Improvement over DDR400
DDR400	2.78	N/A
DDR436	2.8	1%
DDR480	2.8	1%

Memory Speed	Cinebench 2003	% Improvement over DDR400
DDR400	636	N/A
DDR436	639	0%
DDR480	641	1%

Even SPECviewperf 8 barely showed any performance increase (from 0 - 2%), and that suite of applications tends to be quite dependent on memory performance.

Video Encoding

DivX and Windows Media encoding tests have always been very memory bandwidth sensitive. Let’s take a look at the impact of the new memory dividers there:

Memory Speed	DivX 6 + AutoGK	% Improvement over DDR400
DDR400	50.6	N/A
DDR436	51.3	1%
DDR480	53.2	5%

With a 5% improvement in performance, DivX 6 gives us the first indication of any truly tangible performance increases due to the higher DDR speeds unofficially supported by the new chips.

Memory Speed	Windows Media Encoder 9 (fps)	% Improvement over DDR400
DDR400	4.22	N/A
DDR436	4.24	0%
DDR480	4.28	1%

The same success isn’t seen in our WME test, with a 0 and 1% increase in performance at DDR436 and DDR480, respectively.

Gaming

Doom 3 is also a very good measure of the impact of memory bandwidth, as are most other 3D games:

Memory Speed	Doom 3 (1024 x 768 fps)	% Improvement over DDR400
DDR400	121.9	N/A
DDR436	124.3	2%
DDR480	127.2	4%

Finally we see another situation where there’s a positive impact in memory performance. Here, DDR480 gives the X2 a 4% increase in frame rate at 1024 x 768. However, cranking the resolution up to 1600 x 1200 cuts that improvement down to 1%. The usefulness of the 10x7 numbers is in simulating situations where you are less GPU bound.

Overall, we’d say that there’s not that big of an improvement from using DDR480 with the Athlon 64 X2 4800+. The biggest performance boosts will occur in video encoding and games where you are not GPU bound, and even then, you should expect an increase in the 3% - 5% range.