What do these overclocking numbers mean?
I read the beginners article in this forum, and it didn't answer my question. I see people talking about how they set up their system, and it always has a set of numbers like 6/2/2/2 or 6/2/2/3/ or 5/4/3/2 or whatever. What are those numbers for?
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Using 2-3-4-5 as an example, they are found in your bios (sometimes under 'chipset configuration') and represent:
2 = CAS latency, lower is better, 2 is usually the lowest option
3 = RAS to CAS delay, lower is better, 2 is usually the lowest option
4 = RAS precharge, lower is *usually* better, 2 is usually the lowest option
5 = DRAM precharge delay, 4 is usually the lowest option but most memory modules won't run at 4. *generally* lower is better. Some AMD systems with nForce2 chipset run fastest at 2-2-2-11.
Sometimes the numbers are in different order in the bios but this is the most common configuration.
Again generalizing, 2-2-2-5 is usally the best timings for a fast system but it normally takes high quality RAM to run these timings. Unless you take charge of these timings, they are set automatically by your computer, which reads the programming module on your RAM and uses default timings, aka SPD. SPD timings for generic RAM usually look like 2.5-4-4-7, tho it varies wildly and that's yet another generalization.
The biggest gain (you guessed it, I'm generalizing again) is usually found by reducing that first number - CAS latency. going from a '3' to a '2' can greatly increase the memory bandwith available to your system and speed things up measurably. Sometimes a voltage increase on generic or cheap RAM can enable tighter (better, lower) timings. I've never heard of anyone frying a memory DIMM by applying more voltage.
This is far from definitive, I suggest doing some searches on 'RAM timings' and doing more reading if you'd like to learn more.
P4 results first, Asus P4C800-E Deluxe motherboard, 875 (dual channel DDR) chipset:
**EDIT all settings are UNBUFFERED (see the bottom post on this page for Sandra memory bandwidth benchmark unbuffered settings.)
UNBUFFERED (see the bottom post on this page for Sandra memory bandwidth benchmark unbuffered settings.)
Somethings VERY wrong with those amd numbers. Check the bios settings and make sure it runs in sync. Also have cpu int enabled.
I get that bandwidth at 150 fsb on the same multi/fsb/cpu. It might not matter in this case, but just a heads up.
MANY thanks for that comparison. That should be in the sticky part. Great stuff!
Edit//** As usual i should learn to read before post. UN-buffered you used, buffered i mixed. My bad.
UNBUFFERED (see the bottom post on this page for Sandra memory bandwidth benchmark unbuffered settings.)
Feel free to cop these for your upcoming article, full unqualified permission, text and or graphics as you see fit.
Infact, i do get SOME difference between 4/4 and 6/6 and that is proof enough for me. Those scores look just fine i would say.
APIC 1.4 enabled or disabled in bios?
Changed sync mode from 4/4 to 6/6, got statistically unimportant difference in results results, though just on 1 run each way which really makes the whole thing unscientific as hell
4/4 Sandra UNbuffered 2-2-2-11 = 1542/1642
6/6 " " " = 1544/1646
The author, Colin Sun, is one of my favourite Canucks - real friendly guy and good enthusiast/writer.
On your rig, my bet is that your memory outruns the cpu.
Is 3 gigs the max it can do? What's the mutli on a 2.4? 15?
If 3 gigs is the max, you have memory that is far better than the cpu. In your case, i would use 200 1:1 at the timings 5,2,2 cas 2 or 5,3,2 cas 2. Try to add some vcore and see if that cpu can do more.
Try to run 1:1 as a goal. With 3 gigs on the cpu, 200 at 1:1 is no problems.