Studio XPS 1647 RAM Question

My 1647 Specs:
Core i5-540M
3 GB 1333 mhz DDR3 RAM @ 1066 mhz
Radeon 5730 1 GB GPU
80 GB Intel X25-M G2 SSD
320 GB Hitachi 7200 RPM HD (Installed in CD ROM slot)
Windows 7 Ultimate x64

I want to max the system out with 8 GB of RAM. The laptop shipped with 1333 mhz DDR3 RAM even though the memory controller in my i5's only supports 1066. I'm looking at RAM online and the 1333 RAM is CL9 but the 1066 RAM is only CL7.

Would I be better off getting the 1066 RAM since the memory controller in my CPU will not go any faster and it has a lower Cas Latency, or should I still get the 1333 RAM?

 

i3/i5/dual core i7 do not support 1333 RAM natively so 1066 is just fine. The newest SB processors go up to 1600 RAM support, but speed isn't a big issue. The faster speeds only make a difference in synthetic benchmarks and maybe shave off a few seconds rendering stuff, you will not see a difference in real world use.

I would say just buy whatever is cheaper, unless the 1333 RAM is the same price as 1066, then just buy the 1333 RAM because it will automatically downclock.

 

The plot thickens:

Something I didn't mention in my system specs in the first post were my experience scores for windows 7.

Processor: 6.8
Memory(RAM): 5.9
Graphics: 6.9
Gaming Graphics: 6.9
Primary Hard Disk: 7.6
Overall: 5.9

According to AIDA64 my RAM timings were 9-9-9-24.

I purchased 8 GB(2 x 4 GB) of OCZ high performance ram @ 1333 mhz since it was three dollars more than 1066 mhz of the same type. The advertised timings were 9-9-9-20 which was the best I could find for 4 GB of DDR3 at least on Newegg.

The RAM arrived this morning and I installed it, booted and noticed an immediate difference. I would not have thought it was possible for my system, especially with the Intel SSD to be any quicker responding to request but it at least seems like it is faster. I hit the windows experience control panel and told it to update the scores. When the new scores appeared I was shocked.

Processor: 6.8
Memory(RAM) 6.9
Graphics: 6.9
Gaming Graphics: 6.9
Primary Hard Disk: 7.6
Overall: 6.8

Remember that the memory controllers in the i5 CPU's that ship with the 1647 only support 1066 mhz RAM. So I was not expecting such a jump in my memory score since, even though the RAM I bought is rated at 1333 mhz, it would still only run at 1066.

I checked AIDA64 again and discovered that my memory timings were actually better than what was advertised at 8-8-8-16 instead of 9-9-9-20.

 

The RAM rating went up because you added more RAM. Again faster RAM is only useful in benchmarks and synthetic benchmarks. And the 1333 RAM downclocks to 1066 as Core i5 IMC doesn't support 1333 RAM.

 

I know the RAM is under-clocked because of the memory controller on the i5 I have. The laptop shipped with 1333 mhz RAM even though it wasn't technically capable of running at that speed.

Does the under-clocked speed explain the better RAM timings?

 

RAM speeds are based on the integrated SPD tables, and there are several options for the BIOS to choose from. For example, the highest performance SPD for you ram is 1333 @ 9-9-9-20, or what was advertised. Another table is 1066 @ 8-8-8-16, which is what your BIOS picked for you because your CPU doesn't support the 1333 setting.

If you would have gotten the recommended 1066 rated RAM, your timings would have been 7-7-7-20, and that would have been faster than the 1066 SPD timings in the 1333 RAM that you got, which is why it was recommended that you get 1066 RAM in the first place. Though I agree with Tsunade, that the speed differences are quite minimal, and that your WEI score change was due solely to the increase in RAM, not the faster speeds. It is not possible to get a score higher than 5.9 with only 4 GB of RAM, so when you upgraded capacity, it 'unlocked' a higher potential WEI score, it didn't get better because the RAM timings are a few billionths of a second faster.

 

I went with the 1333 RAM because it was only a few dollars more and it gave me room in the future to move the RAM to a system that would support 1333 mhz or, God forbid, something is discovered that would let me upgrade my 1647 to a quad core i7

 

Can't argue with that, and the speed difference is minimal. Good luck getting an i7 upgrade though, lol. If you are interested, you can use CPU-Z to read all of your RAM's possible SPD settings to see why it clocked to 8-8-8-16.