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Bios/cpuZ conflicting memory timings reading

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February 10, 2010 7:01:59 PM

Evening,

I'm an avid reader of tomshardware and extremetech and work in IT and strangely enough i've never actually posted in a forum about an issue with my own machine but i'd say i'm fairly new into the world of overclocking and this one has got me stumped.

Specs:
core i7 920 oc'd to 3.67ghz (174x21), D0 stepping, temps/stability are good
gigabyte EX58-UD3R
3x2gb ocz ddr3 running at 1400mhz
gigabytes "super overclock" gtx260, 680/1500/1250mhz
Win7 Professional 64bit

Now here's where i'm stumped.

My ram is rated/in warranty in an XMP Profile of 1333MHz 7-7-7-20 1.65V but my motherboard doesn't support XMP so i've got it manually set to a fsb/memory ratio of 8:9 so it's running at 1400mhz with the voltage set to 1.62V. In the bios it then lists that the timings are 7-7-7-16 however when loading up CPUz it states that the timing in the memory tab that my timings are 10-10-10-23 and in the SPD tab the voltage as 1.5v and the timings between 5-8 in the "timings table" and although I understand tRas, RAS to CAS etc I don't understand what JEDEC and why it has four columns.

Pretty intense question I know.... any ideas?

cheers :) 


a c 80 } Memory
February 11, 2010 12:19:17 PM

The SPD tab lists the timing tables and voltage from the module' SPD, not what is configured in the BIOS. The system probably ignores your very aggressive memory timings because you are overclocking it way too much for what it can actually achieve. In a way this is good and, based on the SPD, to be expected. Why not run them at the JEDEC #3 or JEDEC #4 timings?
February 11, 2010 7:49:53 PM

Roger that - I did a wiki of SPD and JEDEC and understand them now, but what I can't understand is how my memory is rated in an XMP profile at 1333mhz 7-7-7-16 1.6V but 1400mhz doesn't seem too much of an overclock to not achieve 7-7-7-16 timings??

If I drop my memory multiplier from 8 to 6 my memory comes out at 1050mhz and cpu-z then does report my timings as being 7-7-7-16.

If I drop the voltage from 1.62 to 1.5V and keep the memory multiplier at 8.0, memory then being 1400mhz this seems to make no difference to the timings (i.e. they are still 10 not 7).

What I can't understand though is even if I were to run them at JEDEC #4 this would only equate to 1218mhz and quite far off the 1333mhz quoted. Also, my memory is quoted as PC3-10600 which is quite a bit above the "PC3-8500F (533mhz)" quoted in SPD.

My memory is the following:
OCZ Platinum 6GB (3x2GB) DDR3 PC3-10666C7 1333MHz Triple Channel
- 1333MHz DDR3
- CL 7-7-7-20 @ 1.5V (CAS-TRCD-TRP)
- XMP Profile 1: 1333MHz 8-8-8-20 1.6*
- XMP Profile 2: 1333MHz 7-7-7-20 1.6V*
- Unbuffered
- XTC Heatspreader**
- Lifetime Warranty
- 1.65V EVP**
- 240 Pin DIMM
- Optimized for the IntelĀ® X58 chipset / Core i7


Which seems to give the impression 1333 77716 is easily achievable, it is pretty high quality RAM.

Thanks for your reply ghis
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a c 80 } Memory
February 11, 2010 8:09:34 PM

Quote:
If I drop my memory multiplier from 8 to 6 my memory comes out at 1050mhz and cpu-z then does report my timings as being 7-7-7-16.
Can you tell the performance difference, if any? Most likely not.

Quote:
If I drop my memory multiplier from 8 to 6 my memory comes out at 1050mhz and cpu-z then does report my timings as being 7-7-7-16.
It matches JEDEC #3, therefore it's fine.

Quote:
Which seems to give the impression 1333 77716 is easily achievable, it is pretty high quality RAM.
I doubt the system would be 100% stable. XMP profiles include other parameters as well. If your BIOS doesn't support XMP, then stick to JEDEC #3 or JEDEC #4. If you need to maximize memory benchmark results, then try very aggressive parameters, but don't expect a system that's 100% stable. What motherboard do you have?
February 11, 2010 9:53:44 PM

I have the gigabyte EX58-UD3R. It's been pretty good so far and has faired well with other overclockers online.

I guess there's probably minimal difference between 1050mhz 7-7-7-16 and 1400 10-10-10-28. I guess you would probably want to go for the one with the tighter timings as the increase in mhz isn't all that great? I think i'm just going for trying to get the "best" out of it.

Perhaps I should memory benchmark and report the results? Although they could probably be predictable.
a c 80 } Memory
February 12, 2010 1:12:58 AM

If you didn't yet do it, you should read this article: http://www.tomshardware.com/reviews/memory-scaling-i7,2...

You have a good motherboard with a BIOS that seems to be able to keep most people out of trouble when too aggressive memory timings are used. Please note that the best memory modules run at decent timings and 1.5V or less.
February 12, 2010 8:13:02 AM

Thanks for the link - I did read that article previously which helped me in choosing the 1333mhz price point, certainly an extremely useful article.

While I appreciate there's basically minimal difference, I still don't understand how my memory is advertised as PC-10666 but in SPD information on the module is listed as "PC3-8500F (533mhz)"?
a c 80 } Memory
February 12, 2010 11:38:51 AM

Which means that any frequency above 1066 MHz is overclocked. That's the same with most DDR2 RAM where 800 MHz RAM is sold as 1066 MHz compatible. If you read the fine print, they don't certify that it will run on all systems; they usually state that it was tested to work at that speed and that your experience may vary.
February 12, 2010 12:51:30 PM

I know that some of the higher spec'd DIMMs such as DDR3 - 2000mhz etc were just almost like "factory overclocked" versions of the models below and not technically a ddr3 standard speed but I thought that DDR3 10666 was?

Such as listed as a standard jedec spec here?
http://en.wikipedia.org/wiki/DDR3_SDRAM#Modules
a c 80 } Memory
February 12, 2010 8:36:36 PM

Did you notice that the JEDEC specification allows for timings that can vary widely? Did you try JEDEC #4 (609 MHz)?
February 12, 2010 10:08:39 PM

Yeh - and I can achieve those timings.

Another random question, I just had a look in the mobo's manual and apparently it does support XMP profiles?!? But it's not visible in my BIOS - the note says the option won't even appear if your modules don't support XMP but mine definately do. Is there any reason why this might not be visible? I can't find any information in the manual....

Long shot I know, cheers for the replies so far man.
a c 80 } Memory
February 12, 2010 11:11:23 PM

Your modules don't support XMP. If they did, CPU-Z would show those additional profiles, as would the BIOS.
February 12, 2010 11:31:54 PM

I guess I should probably contact the supplier as surely that means I haven't received as the product information states - OCZ RAM with XMP?
a c 80 } Memory
February 13, 2010 12:12:31 AM

It's up to you, but if your system is stable at JEDEC #4 settings, it probably isn't worth it.
February 14, 2010 6:24:46 PM

Thanks a lot for your help by the way.

One more last random question, is there any disadvantages/issues arise from running a high base clock speed and low cpu multiplier? To get my RAM bang on jedec #4 and keep my overclock of 3.67ghz CPU, i'll probably have to raise my base clock and lower the cpu multiplier so everything works with my fixed RAM multiplies of 6, 8 etc.
a c 80 } Memory
February 14, 2010 8:07:07 PM

I'm not 100% sure, but using a higher clock speed and a lower multiplier shouldn't hinder performance. You could run CPU benchmarks to determine which settings provide optimal performance.
!