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RAM, Go for Timings or MHz? [9-9-9-24 2000MHz vs 6-8-6-20 1600MHz]

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September 29, 2010 7:00:46 PM

Hi Guys! Ok so i was wondering which ram is best, 9-9-9-24 at 2000MHz, or 6-8-6-20 at 1600MHz? (not sure how it all works)

And, is it possible to get the "6-8-6-20 1600MHz" and oc it up to 2000MHz?

any help would be real cool, thanks!

9-9-9-24 at 2000MHz: http://www.amazon.co.uk/G-Skill-DDR3-PC16000-2000MHz-Tr...
6-8-6-20 at 1600MHz: http://www.amazon.co.uk/G-Skill-2048-DDR3-1600-6-8-6-20...
6-8-6-24 at 2000MHz!!: http://www.amazon.com/G-Skill-PC3-16000-Enhanced-Perfor... - i wanted this one, but cant find it in stock anywhere :/ 
September 29, 2010 7:32:49 PM

What sort of system (need specs) will this be going in?
September 29, 2010 7:52:00 PM

Most peeps don't OC their memory. What they do is get memory w/ a high enough speed rating such that when the OC their system, the memory can handle it.

For example, I'd say that more has been written about the i7-920 that any other CPU so I will use that in the example below.

CPU Speed = CPU Multiplier x BCLK
Memory Speed = Memory Multiplier x BCLK


At a standard BCLK of 133, (133.33) you have the following:
CPU = 20 x 133 or 2.66 GHz
Memory = 8 x 133 = 1066 MHz

At a OC'd BCLK of 167, (166.67) you have the following:
CPU = 20 x 167 or 3.33 GHz
Memory = 8 x 167 = 1333 MHz (requires RAM capable of DDR3-1333)

At a OC'd BCLK of 200, you have the following:
CPU = 20 x 200 or 4.00 GHz
Memory = 8 x 200 = 1600 MHz (requires RAM capable of DDR3-1600)

You could change that to......

At a OC'd BCLK of 200, you have the following:
CPU = 20 x 200 or 4.00 GHz
Memory = 10 x 200 = 2000 MHz (requires RAM capable of DDR3-2000)

but my bet is you'd get better, more stable overall performance at CAS 6 DDR3-1600 than CAS 9 DDR3-2000

Related resources
September 29, 2010 7:54:01 PM

@COLGeek yea its:

Motherboard - ASUS P6X58D Premium
Power Supply - 800W Tagan TG800-BZ PipeRock Modular
Processor - Intel i7 920 (Bloomfield) Quad Core - 2.66 GHz (i will oc to 4GHz)
Processor Cooler - Corsair CWCH70 Water Cooler
Graphics Card - Sapphire HD5870 Vapor-X OC
Solid state drive - OCZ Vertex 2 60 GB
September 29, 2010 8:06:29 PM

@JackNaylorPE ahh i see, i didn't realise they were related like that. ok cool, so if i was to overclock my i7 to ether 3.8ghz or 4ghz, i would use the 6-8-6-20 at 1600MHz?

would it be worth cashing out for the 6-8-6-24 at 2000MHz? and will the i7 still be at around the "3.8ghz or 4ghz" mark? (i dont want to kill the i7 by over doing it.. hehe)

thanks for the help so far guys!
September 29, 2010 8:11:21 PM

JackNaylorPE said:
my bet is you'd get better, more stable overall performance at CAS 6 DDR3-1600 than CAS 9 DDR3-2000
+1

No matter what you do, the RAM will have zero to a few percent performance change. You probably wont be able to tell without a benchmarking tool. Its not worth spending alot of money on higher speed RAM.
September 29, 2010 8:15:03 PM

Current AMD architecture favors tighter timings over faster speed for
performance increase. Intel, favors neither. That said, neither makes
a significant impact on performance to warrant a major price
difference.

CAs latency refers to how long it takes the RAM to do somethign after
it's given a command. Makes no difference to FPS in gaming, but like
an SSD, it improves system responsiveness.

Stock i7-930 is 133 block, 21 multiplier and 10x memory multiplier.
Though the latter is determined by MOBO not CPU. This fully saturated
1333mhz RAM. 133block speed x 10 memory multiplier= 1330.

To OC above this you'll need to either lower multiplier or get faster RAM.
In general, we recommend DDR3 1600 RAM if you plan on a OC.

Now, the reason why we recommend G Skill RAM is that memory can
perform better than rated speeds. Most companeis sell you RAM that'll
perform at specs, G SKill tends to give you better than you pay for.
So their RAM can run at higher speeds, lower voltages and/or lower
timings than specs. OCZ ATM, is the opposite, hence we don't recommend
them.

High speeds requires looser timings to work. I'll avoid the
tech details as to why, but suffice to say this is a mechanically
imposed limitation. Now, because faster RAM must be of higher quality
to maintain the same latency as slower RAM, they're generally better. As a result, the Trident DDR3 2000 kit that's rated at cas 9
at 2000, can hit CAS 6 at 1600 speeds. CAS 5 at 1333 speeds. This is
why people will buy extremely fast RAM. They're getting higher quality
RAM so they can run it at tighter timings for the speeds they want.

In general, considering the options you have, you can just stick with the CAS 6 DDR3 1600 kit. If you plan on extreme overclocking(over 4ghz) though, you'll want the faster RAM.
September 29, 2010 8:35:27 PM

Get the cheaper RAM, is the moral of this story, as it has minimal impact to what you are trying to achieve. Spend the difference in cost somewhere else in your system.
September 29, 2010 9:13:42 PM

Thanks guys! awesome! i think i got it now.
thanks for "avoiding the tech details" banthracis! :D 

ok so this is where i am: "i7-920" with "G SKill PI CAS 6 DDR3 1600" Overclocked with BCLK 200, i'll have: CPU at 4.00 GHz and Memory at 1600 MHz.

(once i'v actually build the pc i will research this "BCLK 200" etc.)
!