How important is RAM speed?

I tend not to agree with many of the posts here. RAM speed on a desktop can make a big difference but it's typically used rather differently on a server. Programs on a server tend to be smaller but more instances of them. On a desktop they are few of them but they're bigger. On a server RAM's biggest function on a server by far is caching. So quantity matters much more than speed. I'm not trying tosay that you won't get a few more #s on UnixBench or other benchmarking, but in real world use the amount of RAM is going to have a bigger effect (by how much is in cache) than the speed. A real world example is a recent upgrade I did on a 7 yr old mid-range HP-UX box - close to 1/4 mil when bought. Loads were running 4 to 5 with frequent "naps". So I quadrupled the RAM in the system. Loads now run 0.1 to 0.2 with 200 or so active users (interactive real-time transaction processing system with heavy database work). sar -b (system activity reporter) now shows the system is running 97%+ disk read cache hits. And the "naps" are gone. The RAM used ... Reg. ECC PC-133!

And while a company may use desktops, I wouldn't recommend it. Server components including RAM is designed differently (and is actually slower) than the same bus speed desktop RAM in the case of registered memory which holds the data for 1 write cycle in registers. Plus server memory should be Error Checking and Correcting or ECC... How bad would it be to take down the whole server in a kernel panic because of a single bit error? I won't use anything but Registered ECC memory in our systems. It's just not worth it.

More important to me for most servers is the disk subsystem. All our new servers are being configured with hardware-based RAID10 controllers with "RE" or RAID Edition drives. Again server components designed for a different use - WD's RE drives are rated for twice the MTBF than their regular drives.
 
You've got the point. Most people would concern only about the capacity and price, but I think RAM speed and timing is also important. However, I think size is a bit more important than speed. Enough size can increase your program cache or buffer size which make the program run much faster.
 
First of all server has different functionality. Someone is oriented for statical web sites with some information. But if you have a server which is closely oriented to host databases such as Posgresql and etc. I would like to say that sometimes RAM speed become a critical parameter. Think and act!
 
Well first of all RAM speed by itself is largely irrelevant. The memory will operate at a frequency determined by the processor's BUS speed or HT link, etc.

E.g. you buy DDR2 RAM that operates at 800MHz (PC6400, DDR2-800), if you have an Intel processor with a 1066MHz FSB, then the memory will we locked at 533MHz.

In some circumstances you can change memory dividers etc to run your memory at faster speed or even increase the bus speed, but seriously I don't think anyone would touch these sorts of settings in a server environment. Hence you really only need RAM that is "fast enough" for your processor :-)

My 2 cents.
 
Well, of course RAM speed by itself is largely irrelevant. You always have to have to spec ALL of your server's components to optimize its overall performance. :D
 
Steve-Hostirian said:
Well, of course RAM speed by itself is largely irrelevant. You always have to have to spec ALL of your server's components to optimize its overall performance. :D
Click to expand...

This is very true. I cannot stress how important RAM is but you need the other hardware to make the actual system good. I mean you wouldnt wack 8gb RAM into a Celeron server would you? Simples :P

- Many Thanks,
 
General speaking,the single speed of RAM is not the most important.You should have a reasonable integration of these components such as cpu,RAM and hard disk.I think this is a key.
 
Ram speed matters because it will determine how fast the processor can read and write to memory. But I think hard drive read write speeds would be of far greater significance, since they are slower.
 
Getting the faster RAM will make the transfer of information between devices storing information in RAM much faster.
If you want a faster computer, you should get :
1. Get a faster processor.
2. Get a faster RAM.
3. Get a faster hard disk.
 
to be completely honest here, your bottleneck isn't going to be coming from either your ram or cpu (unless your running some crazy ass predict the weather typer deal) its going to be your harddrive. Memory has gotten to the point that it really doesn't matte especially with speeds from ddr3.
 
Ultimately the speed of the RAM vs Hard rive will be sufficient however the amount of ram required can pose a problem for cost, namely most racks have limited provided slots for ram and often use a combination of larger/smaller cards. However a cheaper option that I’m yet to see mentioned is tri or dual channel memory a.k.a 4 x1gb 1600mhz or 6x1gb 1600mhz.

Though as hardware isn’t my department I’m not sure if 2u or 1u racks have motherboards in support of this due to the size though if so it could both provide a significant increase in speed and degrease in the cost of replacements compared to for example 4x 1gb 1600mhz vs a single 4gb 1600mhz and as such provide twice or three times the read/write capacity.

Just another possible option 
 
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