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-   -   Running memory out of sync with CPU... (http://www.nvnews.net/vbulletin/showthread.php?t=87111)

RAY16 02-26-07 01:43 PM

Running memory out of sync with CPU...
 
I'm trying to squeeze a little more performance out of my aging system. Unfortunately, I have generic RAM, and it's an odd number of sticks (3), so it doesn't overclock very well (after a 10Mhz increase in FSB they crap out). My CPU has far more headroom than my memory allows, so I've been running with the memory and CPU out of sync. I know this is a no-no with nForce 2 chipsets because they don't like it when the mem and CPU are out of sync, but I do notice a performance difference.

My question is, how much of a performance impact does running out of sync really have on nForce 2 chipsets? Would it be worth it to risk having my memory explode on me by trying to push it higher?

buffbiff21 02-28-07 08:33 PM

Re: Running memory out of sync with CPU...
 
Quote:

Originally Posted by RAY16
My question is, how much of a performance impact does running out of sync really have on nForce 2 chipsets? Would it be worth it to risk having my memory explode on me by trying to push it higher?

On my Intel-based nForce board, anything other than 1:1 is a nono. I know with AMD it is different - I am guessing this is the same for ALL nForce chipsets though; I would suggest running tests on your system with the ram in sync (Super Pi) and then test it at the same clock speed but out of sync. See for yourself, as I am unfamiliar with your exact chip. :p (heh sorry..)

It would most definitely not be worth risking your memory - if you think about it, youre really only sacrificing a couple FPS in games maybe?

RAY16 02-28-07 11:56 PM

Re: Running memory out of sync with CPU...
 
I'm too lazy to go back and forth and do tests with it in/out of sync. I can tell you that even with it out of sync there is an overall performance increase. Various memory intensive things might take a hit (haven't really done any tests), but overall performance is up. I can run some HD video that I couldn't run before the overclock.

Xion X2 03-01-07 02:17 AM

Re: Running memory out of sync with CPU...
 
Quote:

Originally Posted by RAY16
I'm too lazy to go back and forth and do tests with it in/out of sync.

Ah, c'mon. It takes a few minutes to enter your bios and change a setting and run a 1M instance of SuperPi. In 15 minutes you could have all the results you need.

Optimizing a computer isn't for the "lazy." It involves hard work and dedication, and it doesn't get much easier in the enthusiast community than running a few SuperPi benches back to back.

SLippe 03-01-07 07:12 AM

Re: Running memory out of sync with CPU...
 
It's been my understanding that if you have more than 2 chips of RAM, it's difficult to overclock it or even run it at 1T for that matter. I'm sure it varies however. I have 4 sticks of Value Select Corsair RAM and I have to underclock it when overclocking my CPU. Hence the current 173 divider. Sucks. I plan to go to two 1GB sticks in the future to correct this problem.

Dazz 03-01-07 01:24 PM

Re: Running memory out of sync with CPU...
 
If it is a Athlon XP it's best to use 1:1 otherwise your bandwith will drop, with Pentium 4's it's fine same goes for Core2's, Athlon 64's perfer 1:1 also for best resaults however if you are CPU limited CPU clock speed will matter the most. When you become GPU limited then overclocking the GPU and FSB/Memory.

swaaye 03-01-07 01:52 PM

Re: Running memory out of sync with CPU...
 
Ya, Athlon XP will take a dive if you run the RAM out of sync. You can get better latency and bandwidth with some chipsets in sync vs. even a higher RAM clock.

nForce is particularly weird cuz its "dual channel" isn't really quite such at all. The 3 DIMM dealie is a major clue-in. It is by far the fastest if you keep the RAM clock and CPU FSB in sync. The chipset has 3 memory controllers. It is designed to be really great for an IGP, cuz the IGP can have its own controller or two, basically, I believe. For the CPU, it's not as useful (especially cuz the FSB isn't able to take advantage of dual channel bandwidth anyway).

Some of the later VIA chipsets, on the other hand, are ok with a higher-than-FSB RAM clock. I believe this is caused by some buffering prefetch mechanism in the chipset that can take advantage of the lower latency and higher bandwidth RAM.

RAY16 03-02-07 12:02 AM

Re: Running memory out of sync with CPU...
 
I'll take all suggestions into consideration, and then decide what to do. Thanks for the responses.


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