Is greater memory bandwidth worth for a cheap processor?

Hi. I'm planning to buy an Acer 3050 with:
*Sempron 3500+, 2GHz, 128 KB L2 cache
*512 MB PC2-4200 memory
*80 GB 5400 rpm HD
*DVDRW
*on board ATI Radeon XPRESS 1100 with 128 MB shared memory

for 1710 reais (about 906 US dollars)

I can get 512 MB more memory for 90 reais (about 48 US dollars). The seller doesn't seem to know what is dual channel, but since the Acer website claims the 3050 model supports dual channel, I suppose that these two 512 MB sticks with equal speed (filling all of the two memory slots in the notebook) will get me dual channel.
The seller has not yet told me the price of PC2-5300 memory.

My doubt is: Will I have a real benefit (worth 48 dollars for a poor guy) with the additional bandwidth of dual channel? Does a Sempron 3500+ use all this bandwidth? I don't think I will have much benefit from the additional *amount* of RAM, because I use lightweight apps and often don't even hit swap... I think that the additional amount of RAM will only help me as additional disk cache.

And what about PC2-5300 memory? If I get it for cheap, will it actually speed up the notebook?

I will use it with Linux.

 

The extra memory will not over power your CPU, do you need it different question. Many have stated 512MB works with XP. So may be fine for light apps with Linux. One problem is ATI will set aside 128MB of system memory so you really only have 384MB, you still might be ok. Buying a faster RAM stick well revert back to the slower one, and don't worry to much about “dual channel” if 512MB works, ok to run with 1 stick. I would by and then see if you need.

 

The on-board GPU is sharing the system memory and, based on my tests with the ATI 1250M, I would expect you to get better graphics performance if you have two similar RAM modules. This may be more noticeable than the improvement in the CPU performance. I would also recommend that you get more than 512MB so that the integrated GPU can have a reasonable amount of memory.

Most PC4200 RAM has a lower latency (CL=4) than the PC5300 RAM (normally CL=5) so the actual speed difference between the two types of RAM is quite small.

John

 

More RAM is most important. Usually it is not the RAM that is the performance bottleneck so I don't think you will notice a difference between single- and dual-channel RAM.

 

I don't plan to use the 3d card for more than showing 3d screensavers, if that... I will probably choose lower amount of memory for it (on board cards allow you to choose how much memory to share AFAIK).

Regarding CL: AFAIK the CL is measured in clock ticks. So, in nanoseconds, CL=4 at 533 MHz is equal to CL=5 at 666 MHz, because 4/533 = 5/666
So the 666 MHz memory has the same latency, but more sustained bandwidth. My doubt is, does it result a sizable increase in overall system speed? I read somewhere that AMD processors with integrated memory controllers are more sensitive to latency that bandwidth... So ... Is it worth?

NOTE: I'm not confident about what I said in the above paragraph.

 

I don't agree about "revert back to the slower one": if I do buy two sticks, I'll buy them with the same sped. Either two 533 MHz or two 667 MHz. The doubt remains: does dual channel result in a significantly better overall system performance with this processor?

Oh, and if I put more RAM in the notebook after I buy it, I lose warranty... But perhaps that's what I'll do. Perhaps I'll buy it with 512 MB and, if I want the additional stick, I'll buy it in a year when the warranty ends.

But I still would like to know beforehand if the additional bandwidth will have a significant benefit...

 

Revert back to slower speed is fact. Does not matter because you said you will buy 2 of the same. Chaz said dual not that big of deal, I agree. If you buy RAM after purchase you run the risk of no dual channel but not big deal.

Now warranty, I never heard that but if I had a problem I would remove 1 stick b/4 I took it in.

no one can tell you the main question you ask for sure, it certainly would not hurt.

 

1. Normally, the warranty covers the RAM which the computer comes with. It is unusual if the warranty excludes you adding more RAM. If you encounter a problem then just remove the extra RAM before asking for warranty service.

2. See the attached PDF file for PCMark05 results for 1 x 512MB and 2 x 512MB in a Samsung R20 (T2250 CPU + ATI 1250M chipset). There was a massive difference in the transparent windows results, but the virus scanning result is also significantly different.

John

 

The problem is opening the notebook to put more RAM. The first store I visited told me they cannot do it without voiding warranty; only the manufacturer can. I'll try to better inform myself of practical ways of adding RAM without losing warranty.

 

That is interesting. Is there anywhere I can find a discussion about those results?

I suspect that the difference in those numbers was because of the amount of RAM, not speed. That is because most of the non-3d tests show no difference, but some show significant difference. I think that if the issue was memory speed, it would affect the tests more equally... but memory size does not affect tests equally.

 

I haven't seen a detailed description of how to interpret the benchmark results.

I agree that the 512MB result is limited by the RAM, including the small (64MB?) allocation to the GPU.

I've looked through my results collection and have updated the table to include some more combinations. Unfortunately, I did not try 1 x 512MB PC5300. The results also show some inconsistency but there is no significant overall difference between 2 x 512MB PC4200 and 2 x 512MB PC5300.

As for upgrading the RAM, most manufacturers now show this in the manual. The RAM is usually under a cover on the bottom of the notebook.

John