Tuning latency.

[Wipster]

Hey all,
My overclocking experiance sofar has been mostly the max FSB hunt with a low multi to get my max cpu speed. But there are better options that can reduce the latency of my system and increase my memory thoughput, this is what I am trying to explore at the moment but I need a bit of a hand as I am having a few troubles.

For reference here is some of the material I have been reading focusing around tRD and CAS latencies.
http://www.anandtech.com/showdoc.aspx?i=3190&p=12
http://www.anandtech.com/mb/showdoc.aspx?i=3208&p=5
http://thetechrepository.com/showthread.php?t=195

That done, here is the system in question.
Processor: E4500 (Max freq 3.4Ghz)
Mobo: GA-X38-DQ6 (Max fsb <450Mhz, limited by CPU wall)
RAM: Crucial Ballistix 2x2Gb PC2-6400 4-4-4-12 (Max freq was 900Mhz :/ )

As stated above I think I have found the maximums I can get in each device at voltages and heat I am comfortable with it just a matter of ballancing them. To find the best CAS I was a bit unsure so I set the voltage to what I wanted (sticks are rated 2.0 +-0.1, so 2.1v) kepped the timings 4-4-4-12-2T and then upped the freq on them, that sound ok?
Edit:- This seems to change every day, it wouldn't give no errors at a measily 880Mhz with CAS4 (9ns) today, grrr.

In my exploration to get lower tRD, before I started playing with the ram too much I compiled a table which gave the latencies and mem read at different FSBs and strappings which gave a mem speed of 800 (4-4-4-12) or 1000 (5-5-5-15)

As you can see the latencies never got very low, worse then stock settings atm of 54.4ns, so I must be doing something wrong. The throughput is 2Gb/s faster caompaired to stock in the bottom case, so it was working ish.

The main problems I have had was with bottom entry it was ok going up to it, with rebooting and coming up with lower timings etc. But from a cold boot my mobtherboard just had a beeping fit and resets. I have noticed this with trying to tune my memory, I work up to a frequency then change something it beeps, revert back to the old working and it beeps and resets again. Its very odd and a bit frustrating.

So thats where I am at the mo, any help or advice would be greatly appriciated. Thanks for reading this text wall.
Best Regards,
Wip

 

[Wipster]

Hey again,
Quick question about latency as I think I have stabilised my settings somewhat, I have overclocked my ram to 1066 5-5-5-15, seems to be stable and I cant get further. And I have tuned down my tRD to 7 but my memory latency is still slower then my default 400mhz fsb 1:1 by 7ns where could this extra latency be coming from if I am running faster and tighter. Dont like the idea the motherboard can do a better job then I can.

 

[Wipster]

And another perplexing thing, if I run with a bit of an overclock on the ram and everything on auto in the advanced timings. I read the values auto has set with memset then I set them manually in the bios it just beeps at me when it tries to boot and resets, has anyone else seen this or have any idea why auto sets them fine but I cant?

 

[BillParrish]

And another perplexing thing, if I run with a bit of an overclock on the ram and everything on auto in the advanced timings. I read the values auto has set with memset then I set them manually in the bios it just beeps at me when it tries to boot and resets, has anyone else seen this or have any idea why auto sets them fine but I cant?

Find and run SPDtool (used to be on techpowerup site) for an insight to the SPD settings not found in the maunal bios settings. Long story short, there are a lot of things despite your advanced bios settings that the bios sets either automatically based on tables/settings embedded in the bios or from the SPD that you have no control over.

I have not commented before because my board has nowhere near the options found in your bios and it was not nearly as complicated to determine my best settings by mainly trial and error with only a little testing. Also while delving deep into memory subsystem details is a good thing you will want to, in most users cases, run the cpu as fast as possible because a 100MHz of cpu speed will offset a significant amount of increased memory latency in most cases.

The 425 x 8 at CAS 5 looks like the winner even if you have to drop to 420-422 for stablitly. If it will do it. 2GB ram modules to this day continue to stress the MCH/board design and prevent optimal settings compared to running 2 x 1GB. (which none of us want to do anymore)