Memory timings query

Bigmonty

Bigmonty

Bigmonty

Associate
Joined
6 Mar 2007
Posts
113
Hi

I have 4 sticks of the following RAM

PC6400 DDR2 800Mhz, CAS 4-4-4-12
- Hand-picked BGA 64Mx8 Chips
- 240pin, Non-ECC, Un-buffered DIMM
- Racing-Orange Aluminum Heat Spreader
- Retail Package
- Lifetime Warranty
- Working Voltage: 1.8v ~ 2.3v


However if I leave my Bios on auto it sets the timings as 5-5-5-31.

I go into my Bios and change the timings to 4-4-4-12-1T and the PC then doesn't post. I go back in and alter it to 4-4-4-12-2T and it works fine. What is the difference between 1T and 2T and is one safer than the other. Incidently I also set the voltage on the memory to 2v rather than leaving it on auto.

Cheers
 
Now someone might be able to tell you better than me about this, but if your using 4 sticks of RAM then 2T is necessary to get the performance your after, leave it 4-4-4-12-2T and you should be good to go. It has something to do with the RAM controller having to address the extra 2 sticks of RAM so needing that setting.

Hawker
 
Command rate adds extra clock ticks between selecting a memorychip, and making a read or write to it. When you have 4 (or more) sticks of ram, increaseing command rate from 1T to 2T slows it down a little, but relieves a lot of stress on the memory controller.

In effect, it slows down the first read or write to any selected memory chip, but if several reads/writes are made to the same chip, it makes no further impact, so 4-4-4-4-12-2T should be faster than 5-5-5-5-12-1T.

In a perfectly designed motherboard, 2T shouldnt be needed. But perfect designs are rare, as comprimises have to be made during motherboard design to actually fit everything on the board, have sufficient cooling, clean signal paths, and reliability etc.

4-4-4-4-12-2T should be plenty fast enough.
 
Last edited:
That helps. Thanks a lot for your replies.

As for voltage I am assuming 2v should be enough? Is it safe enough to up it to 2.3v if I find memtest as errors later on? What strain does that put on the motherboard?

Cheers
 
Well if it says on the manufacturer website its ok with 2.3v then giving it that much shouldnt be a problem, personally I dont like going above 2.2, it shouldnt strain the mobo particularly putting more volts through the RAM, so long as the RAM is upto it then it should be fine.

Hawker
 
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