Ram | CAS 2.5 @ DDR333, or CAS 3 @ DDR400?

[Mr Bob]

I have a dilema, mainly because I don't know about speed/cas latency when dealing with ram.

What differences will one see with CAS 2.5 @ DDR333, when compared to CAS 3 @ DDR400?

 

[Markfw]

Get the DDR400. How many sticks do you plan on using and what size ? And why do you have the prices listed on all your components in your sig ?

 

[t3h l337 n3wb]

You have 4 sticks of RAM already right? Is this for someone else? If so, definitely get the DDR400. CAS latencies don't really make that much of a difference.

 

[Mr Bob]

" Get the DDR400."
- That's what I figured, but I wanted to know the reason why.

"How many sticks do you plan on using and what size ?"
- I thought that cas latency made a pretty large difference. It would be two 1gb sticks, or four 512mb sticks.

I ask simply because my motherboard seems to turn 4 x 512mb DDR400 sticks into DDR333, reference: http://www.msicomputer.com/product/p_spec.asp?model=K8N_Neo4_Platinum&class=mb

"And why do you have the prices listed on all your components in your sig ? "
- So I know what I paid, and others can see too.

" You have 4 sticks of RAM already right?"
- Yes I do, but I am sure that I could sell them for what I paid, and then grab two 1gb sticks. I went for the 512 simply because of a better cas latency.

 

[Brunnis]

Actually, the access times will be the same in this case. Latencies are given in number of clock cycles, so the final access times are determined by the clock frequency. Example (using the memory speeds and timings from the initial post):

DDR400 = 200MHz => clock period = 5ns
DDR333 = 166.7MHz => clock period = 6ns

DDR333 CAS 2.5 => 6ns*2.5 = 15ns access time
DDR400 CAS 3 => 5ns*3 = 15ns access time

So, you will have the same access times, but much higher bandwidth with DDR400. In other words: DDR400 will be better. Please note that this doesn't take into account the rest of the memory timings. Chances are that the overall memory access times actually will be lower with the DDR400 memory.

 

[Mr Bob]

CPU-Z shows the "Frequency" under the memory tab, mine is set at 158.0 MHz, which means it is running as DDR333 (according to what you said above), instead of DDR400 like it should.

It doesn't seem like there is anything I can do about it either, on the MSI website, it lists that the max is 333 for 4 double sided sticks. 🙁

 

[t3h l337 n3wb]

An X2 should be able to run 4 sticks of DDR400 at 400mhz. The memory controller is integrated onto the die, not on the motherboard. Also, even if for some reason it can't, just up the FSB a bit or set the divider higher.

 

[Mr Bob]

The CPU seems to be fine, but the MSI link above says it will operate at DDR333.

"just up the FSB a bit or set the divider higher. "
- Just go into the BIOS and increase the voltage?

 

[t3h l337 n3wb]

The board should be able to run 4 sticks @ 400mhz just fine. The website is probably just outdated because of the older Winchester memory controllers that could only do 333mhz. Upping the FSB will overclock your CPU and RAM FSB. If for some reason you don't want to, you can just set the divider higher. Either way, you don't have to increase the voltage on anything. Overclocking doesn't always involve voltage increases. Only higher clocks require more volts to be stable. For example, my 3200+ Venice is running @ 2.5Ghz (25% overclock) just at stock voltage. It has absolutely no "harmful" effects on my CPU. Overclock isn't as "dangerous" or "hard" as most people believe. If you just increase your FSB by 1, you've overclocked your system.

 

[Mr Bob]

What setting should I mess with to make the ram run at DDR333 instead of DDR400? Any tutorials I can review?

 

[t3h l337 n3wb]

Well, you could always learn how to overclock 🙂 If you don't want to though, your mobo should have memory dividers past 200mhz. So just select the one above 200 (dunno what that would be), and test it. If it's still not at 200, then keep bumping the divider up til you hit a number close to 200. That's basically overclocking your RAM.