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Untitled Document
Memory Performance Analysis
Memory performance is not down to the memory alone. In a lot of cases, it is
restricted by the chipset. It is this key point that helped differentiate one
chipset from another, as memory performance affects overall system performance
considerably.
With the Athlon 64 architecture, this is no longer an issue. The memory controller
is now integrated onto the CPU die and can bypass the north bridge entirely.
This means that performance from chipset to chipset is almost negligible. Price
and features are now where it matters.
Intel on the other hand, still rely on the north bridge, so there is still
a difference from chipset to chipset.
In order to understand the impact of memory performance, we have taken a fairly
scientific approach to showing difference between low and high latency memory,
DDR2 and DDR, dual channel memory and of course different frequencies.
In order to do this, we used the incredibly capable Asus P5GDC-V Deluxe motherboard,
coupled with a 3.6GHz Prescott processor. This LGA775 motherboard has the 915G
chipset and has support for both DDR and DDR-II memory. This makes it an excellent
test bed for our memory comparisons. We used an nVidia reference 6800GT (PCI-E)
clocked at 400/1100 which is the same speed as a 6800 Ultra. This helps remove
any possible bottlenecks. The latest drivers were used, including the latest
BIOS from Asus.
Aquamark and 3DMark were all left at default settings. Doom 3 Low setting represents
640x480 with no AA or AF, at a “High” texture level. Doom 3 High setting represents
1280x1024 with 2x AA and 2x AF, at a “High” texture level. UT2004 Soft, represents
UT2004 running in software rendering mode at 1600x1200 which is not 3D accelerated
– this puts a lot of strain on the CPU and Memory. UT2004 High represents 1280x1024
with 3D acceleration.
During all these testings DDR was kept at X-4-4-8 and the DDR-II was kept at
X-4-4-12, where X is the CAS latency..
DDR vs DDR-II
|
400MHz
DDR, C3, Dual Channel, 2 x 512MB |
400MHz
DDR-II, C3, Dual Channel, 2 x 512MB |
533MHz
DDR-II, C4, Dual Channel, 2 x 512MB |
| Aquamark
Overall |
60,131 |
60,001 |
61,191 |
| Aquamark
CPU |
9,494 |
9,454 |
9,999 |
| 3DMark
03 |
11,115 |
11,094 |
11,194 |
| 3DMark
01 |
20,359 |
20,329 |
21,013 |
| Doom
3 Low |
77.3 |
76.2 |
79.6 |
| Doom
3 High |
69.0 |
68.7 |
69.8 |
| UT2004
Soft |
17.05 |
16.97 |
17.24 |
| UT2004
High |
132.87 |
133.23 |
137.13 |
When DDR was originally released, there was initially very little improvement
over SDR. It was only until the processors got faster that the benefit was seen.
As you can see, when compared like for like and with the same latency, the differences
are hardly noticeable with 1fps being the biggest difference in Doom 3 High.
We can only predict this is a similar situation.
However, DDR-II memory comes in at 533MHz C4 as standard, so a like for like
comparison is hardly fair. When compared at these speeds, we can see DDR-II
offers a benefit, but very minimal – 4% at most.
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