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Ram timing and basic thoughts

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  • Memory
  • RAM
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Last response: in Memory
May 12, 2010 11:50:17 AM

i just have a simple question about RAM.

would someone please explain to me what timing mean in ram like, 7-7-7 24 or whatever.

just started to get involved in computer parts (been working with programs till now) and i just want to get to know the parts better.

so i would like to know what that means and how do you check what the timing on your ram is and its mhz frequency.


this is the pc i have as of now tell me your thoughts. bare in mind that this is my first build

I7 920
G.SKILL 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Triple Channel Kit
Two Caviar Blacks in raid 0
GTX 280
EVGA Micro ATX X58 SLI/Crossfire
Antec 300
Coolermaster 212 Plus
Corsair 650w

please tell me your thoughts

Thanks again to all

More about : ram timing basic thoughts

a b } Memory
May 12, 2010 12:11:13 PM

RAM timings, aka latencies, is a measure of how long it takes for the memory to relay information back to the CPU. The higher or looser the timings, the worse, as it takes longer for the RAM to relay information to the CPU, and thus, slows down the performance of your PC. Normally the lower the latencies, the more expensive the RAM. Also, tighter/lower memory timings provide a more noticeable performance boost than higher speed RAM.
May 12, 2010 1:53:35 PM

Lmeow said:
RAM timings, aka latencies, is a measure of how long it takes for the memory to relay information back to the CPU. The higher or looser the timings, the worse, as it takes longer for the RAM to relay information to the CPU, and thus, slows down the performance of your PC. Normally the lower the latencies, the more expensive the RAM. Also, tighter/lower memory timings provide a more noticeable performance boost than higher speed RAM.


Thanks for the reply, it really help me understand what it means.
I would also like you to know why are there so many numbers and what each of them means.


P.s what counts as good (fast) timing and what counts as bad (slow) timing.
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a b } Memory
May 12, 2010 2:26:10 PM

Each of those numbers stands for a different parameter:

What happens when accessing memory:

Step 1. tRCD (RAS to CAS Delay) - The row is selected by the Memory Controller. A typical number for DDR3 is 7

2. CAS (Column Address Strobe) - The Memory Controller selects the column and now the ROW is ACTIVE, and the READ COMMAND is sent.

3. Data is sent to the DQ pins after CAS delay.

4. tRAS (Row address Strobe): The module waits a certain period of time for the data to be active. Call it 24 for typical DDR3.

5. tRP (RAS precharge) 2 cycles, The Memory Controller DEACTIVATES the row. 7 again.

6. Memory Cycle repeats as requested by the Memory Controller.

The timings I mentioned above are represented as: 7-7-7-24 1T (CAS, tRCD, tRP, tRAS) The 1T is the command rate: This is how long instructions are presented to the memory modules. 1T means instructions are presented for only 1 cycle. 2T is 2 cycles.


Since these numbers represent how many clock cycles it takes to perform the action, larger numbers are slower. But at the same time, larger numbers allow more time for the function to actually complete: So they tend to be more stable.




Regarding what counts as good/fast timings versus slow timings; it depends on the type of memory. For old school DDR memory, 2 and 3 are typical timings. For DDR2 you're more likely to see 4 to 8. For DDR3?? 7 and looser. The reason for this is that - as clock speeds increase - it becomes easier for a function to not complete in the shorter timespan. So timings have to be loosened to ensure the given functions can complete reliably.
May 12, 2010 3:24:45 PM

Scotteq thats exactly what i wanted to hear thanks a lot for the reply!

i did want to know what the 24 mean in a 7-7-7-24 1T.

also what do you think of my build that I posted before

though i will say there are a lot of terms there that i dont understand but i will try to read on!
a b } Memory
May 12, 2010 4:28:46 PM

Your build looks fine :) 
May 12, 2010 5:12:30 PM

Scotteq said:
Your build looks fine :) 


Thanks again!

a b } Memory
May 13, 2010 1:45:00 PM

Are you going to Overclock? And if so, what is your target?
May 14, 2010 1:12:34 AM

Sorry for hijacking this thread, but I'm researching RAM for an i7 build myself...

My future rig: (Digital Audio Workstation use only)
i7, Win7Home-64bit
MOBO: ASUS P6T Deluxe V2 [memory standard: 1600(o.c.), 1333]
PS: Corsair TX650, Case: Antec P180, Thermalright Ultra120Extreme1366
HIS H467PR1GH Radeon HD 4670 1GB PCI-e(for dual monitors, & Maxivista+networked 2nd PC for third monitor)

No plans to overclock.

Want 6GB DDR3 triple channel RAM. Looking at G.Skill.

Would it be better to get the 1600 with 9-9-9-24 or the 1333 with 7-7-7-18?

They are both essentially the same price (only $10 difference).
The 1600 memory with the 9-9-9-24 is on ASUS's QVL. The other isn't. (QVL updated Oct2009)
Which would be the choice you'd make?

Also, everthing look ok with this rig? I've been scouring the forums/internet... and come up with this so far. Any suggestions greatly appreciated.
June 21, 2010 1:08:17 PM

Like Im hearing from this thread and many others,timing generally is better on stable ram that has set timing from factory with lower (tighter)speeds vs higher (looser)timings at more speed.But if you are overclocking you could get a higher speed ram and increase timing through the BIOS but then you might have a unstable ram setting that would not post or boot.Its all in looking at reviews in the place you are buying it from and comparing it to your system and if anyone has sucessfully overclocked and/or increased thier ram timing on that particular set of ram while being stable.To me I would go with more stable ram at higher speeds and gradually try to increase the timing,making sure not to crash.Most motherboards nowadays have a memory reset option so if you dont post you could just reset the cmos or in my case with the asus 890gx pro boards have a memok button on the board that does it automatically.So more stable higher speed ram like a 1800 mhz with 9-9-9-24 could be increased to 8-8-8-24 timing or better and still be as good as ram with tighter lower timing with less speed.It all depends on if you are willing to overclock and adjust it and be comfortable with the occasional non post or crash if set too high.
a b } Memory
June 21, 2010 1:57:38 PM

I'd like to point out that it will take a very good system benchmark to distinguish between 8-8-8-24 and 9-9-9-24 RAM.

Don't obsess. :) 
June 22, 2010 11:31:11 AM

Very true,but some people that cant afford any more for thier computer do obsess and are perfectionists like me.I need that little bit of extra umphh blaamm just to see a difference.It could be the obsession of experimentation.It gives us a kick to see even the smallest difference knowing that we can do it ,lol.But you are right jsc,I guess the only reason Im saying this is,I called directron and spoke to a customer satisfaction guy who had no idea what he was talking about when I asked him the difference between a mobo running on 2x 8x pice ports or one that runs one slot at 16x and the other at 4x,he said there was no difference and argued with me (the customer),what an idiot,they lost a customer and I went straight to newegg lol.