Correct my terminology

spleewars

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Aug 16, 2009
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i do have some questions to ask:

- CPU VID Control, VCC, CPU Voltage mean the same?

- i got 8gb xms ddr2 800mhz ram but i still cannot understand what are the dividers. What do you suggest for my ram?

- plrease correct me if i am wrong, which propably i am, reading in the thread i saw this phrase "The basic process is to try different Vcc values keeping the other vcores constant. " Does this mean there is an option to set seperate voltages for each core? So what is the true meaning of VCC?

- a lot say not to leave settings on auto but what 's the most to avoid leaving on Auto?

- as allrounder, what is the best otpion to run prime95?

Thanks for your time guys despite the same questions are repeated million times.

Marco
 
One problem is that different motherboard manufacturers use slightly different expressions for the same terms.

What motherboard and CPU do you have? I am guessing that because you mentioned "VID" that it is an Intel Core2 system.

#1. VID is fixed. It's the value of the voltage from the motherboard voltage regulator that is hard wired into the chip. It will vary from chip to chip. Lower is better because it gives you more OC headroom to the maximum voltage you can use. "VCC" and "CPU voltage" are not always equivalent. More confusion. :(

#2. Dividers are the ratios between FSB and memory frequencies. I always run 1:1, FSB frequency : memory clock. Stand by for more confusion. :) Remember that we are talking about DDR2 RAM here. DDR2 transfers two chunks of data each FSB cycle.

So to run at 1:1, the memory clock needs to be two times the FSB frequency. If for example, you have an E8400, stock FSB 333 MHz. If you have a Gigabyte motherboard, set your System Memory Multiplier to 2.0 and your memory clock will change to 666 or 667 MHz. And as you increase the FSB, the mem clock will track.

#3. What we want to do is increae the FSB until the system does not boot, then increase the CPU vcore. All CPU cores run at the same voltage. But sometimes you have the option of also increasing the voltages applied to the north and south bridge chips.

The meaning of VCC depends on context. Sometimes it means the 5 volt PSU output. Sometimes it means "CPU voltage". If you mean "the voltage applied to the CPU cores", the most precise term probably is "CPU vcore".

#4. Auto settings (what I do):
All voltage settings on MANUAL. I may leave them on their default values and not change them, but I take them off AUTO. Set vdimm (memory voltage) to factory recommended values.
System mem mult: off AUTO and for DDR2, set it to 2.0.
DRAM timing, I do leave on AUTO. Optimizing memory timing is the last thing I do when overclocking.

#5. We use Prime95 to test for stability. It loads all the CPU cores to 100%. Among other things, this will drive temperatures up. If a system will run P95 for a while without crashing or stopping while staying under some particular temperature, that system is considered "stable".

The first problem here is how long is "a while": 2, 4, 6, 8, 12, or 24 hours? I used to test for 12 hours, but one time, I just let one of my systems run overnight. Discovered that it stopped on an error after 14 hours. So now I test for 24 hours.

If a system stops running P95, you have two choices, dial the settings back a little or increase voltage somewhere and try again.

If you are going for a maximum OC, everything matters - CPU VID which is luck of the draw, choice of cooler and case, motherboard, power supply, layout inside the case.

You also need to look at this if you haven't:
Core 2 Quad and Duo Temperature Guide
http://www.tomshardware.com/forum/221745-29-core-quad-temperature-guide
 

spleewars

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Hi Jsc, thanks for your detailed reply. In fact i was really doubting about the VID option and how i have a clear understanding why.

Another quick question anybody : setting my ram to 4-4-4-12 is better than 7-7-7-18? Or leave them auto?
 

bryanbee

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If your starting out overclocking RAM should be the LAST thing you are touching man. RAM is so easy to damage if settings arn't set right and unlike your processor they have no built in get out of jail free cards :p
 
bryan is half right. Leave the RAM alone until last. Actually, RAM is generally pretty durable. If you get aggressive with memory timing, mostly the computer will refuse to boot or the BIOS will automatically reset to a setting that will boot. Generally. :)

If you have OC problems, you can go in and loosen the memory timings to try to make sure the problem is not RAM. "Loosen" means change them so the timings are not as critical. That means larger numbers. "6-6-6-18" is looser than "4-4-4-12".