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Ram for P7P55D. 1333, 1600?

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December 1, 2009 8:25:39 AM

Hey guys,

I'll be building my first pc sometime soon and I've decided on the Asus P7P55D motherboard. The G.Skill ripjaws ddr3 (2x2gb) have a nice price so the question is, do I get the 1333 or the 1600 version? Is there much of a difference? How about the timings? I'm a little confused about the differences :p 

My rest of my build will be Core i5 750, Sapphire HD5850, VX550w, Storm scout casing, Samsung 21.5" lcd, and a basic optical drive. If any of that helps.

Thanks for reading

More about : ram p7p55d 1333 1600

December 1, 2009 8:49:54 AM

ddr3 highest *official* spec is 1600. yet at this moment it is hard to tell if the ram maker overclock dram with 1333 with better batch of chips, or use those fundamentally spec at 1600.

the difference depends on the apps u r using :) 

sometimes qty means more than speed, and then of course stability means more than performance.

if 1600 is within yr budget, then why not max it out.

or go for 1333 if budget a bit tight. i think u'll only loose a few fps, probably within 1 digit. that comes down to how specific games r designed when it comes to ram usage also. i think - not a big lost.

if u go 1333 now, at later stage, u can upgrade yr ram that goes beyond 1600, maybe in 2010-11. maybe overclock yr system then?

imho ddr3 has some serious potential to be really good for oc.



a b } Memory
December 1, 2009 9:00:45 AM

I would suggest, stick to DDR3 1600MHz. 1333 is barely out of DDR2 region. Yes, if budget is a constraint then you don't have an option do you?!!

Also keep in mind the latencies play a really important role in deciding RAM's. CL7 RAM's are lowest available in the market right now, i think.
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December 1, 2009 9:27:48 AM

well it's not about the budget. the price of the 1600 is about $4 more than the 1333 here!

So 2000mhz is pointless if the highest spec is 1600? Im still confused!

Back to reading!
December 1, 2009 1:19:35 PM

1.9 v is a problem..It is well known that the highest safe voltage on all core i5 and i7 CPUs is 1.65v..A review here on Tom's showed that such dimms can operate @ 1.65v but you'll need luck..So its a gamble. 1.9v Ram DIMMs are meant for amd platforms, so I'd aviod them if I were you!
December 1, 2009 1:28:13 PM

DDR3 1600 will give you extra headroom for overclocking but you may still have to slightly downclock it.

DDR3 1333 risk to limit your overclocking, you can overclock it but there is always limitation.

Go with Corsair DDR3 1600 Rams:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...
(Corsair Dominator has a tall heatsink so it might have a conflict with a large CPU heatsink cooler and it might not fit)


or


http://www.newegg.com/Product/Product.aspx?Item=N82E168...


These are good examples of DDR3 Rams which are perfect match for Core i5...
December 1, 2009 2:26:12 PM

I can't seem to find those here in the Philippines. I did however find G.Skill Ripjaws ddr3 1600 7-8-7-24-2N

Is that CL7?
December 1, 2009 4:55:00 PM

Yes, the first number mentioned in a ram timings is the cas latency.
a b } Memory
December 2, 2009 4:51:53 AM

miatchapalooza said:
I can't seem to find those here in the Philippines. I did however find G.Skill Ripjaws ddr3 1600 7-8-7-24-2N

Is that CL7?

This is a good RAM. You can go for it!
a b } Memory
December 2, 2009 5:23:47 AM

hell_storm2004 said:
I would suggest, stick to DDR3 1600MHz. 1333 is barely out of DDR2 region. Yes, if budget is a constraint then you don't have an option do you?!!

Also keep in mind the latencies play a really important role in deciding RAM's. CL7 RAM's are lowest available in the market right now, i think.


Don't oversimplify latency, DDR3-1600 CAS 8 has less response time than DDR3-1333 CAS 7 because its cycles are shorter. And that's what it's really about.

That is to say, DDR3-1600 CAS 8 should always outperform DDR3-1333 CAS 7, while DDR3-1333 CAS 6 will only sometimes outperform DDR3-1600 CAS 8. At least, that's what happens when the memory controller supports both properly.
a b } Memory
December 2, 2009 5:37:06 AM

^^Agreed to the point you made. Just wanted to let the OP know that latency and frequency are both important in choosing RAM's. That's why told him to get CL7 1600MHz. I hope i was not wrong in what i said! :( 
a b } Memory
December 2, 2009 6:44:32 AM

hell_storm2004 said:
^^Agreed to the point you made. Just wanted to let the OP know that latency and frequency are both important in choosing RAM's. That's why told him to get CL7 1600MHz. I hope i was not wrong in what i said! :( 


It's great advice when you can afford to take it!
December 2, 2009 8:10:08 AM

so higher frequency is more important than lower timing? is this correct?
a b } Memory
December 2, 2009 9:06:49 AM

miatchapalooza said:
so higher frequency is more important than lower timing? is this correct?


Not always, it depends on how well the CPU and the program can use the added bandwidth. Generally speaking better timings are more important than more speed, but you do have to do a little math. I'll make this easy for you:

If the platform and program reach peak performance with DDR3-1333, you might still get a benefit in latency by using DDR3-1600. In this case, it's a matter of how long the program has to wait for the memory to be read or written to, and you can't rely on the CAS Latency number without also including the frequency:

DDR3-1600 runs at 800 MHz, so CAS 8 takes eight 800 MHz cycles. An 800 MHz cycle happens in 1.25ns, so 8 cycles is 10ns. DDR3-1333 runs at 667 MHz, so a cycle takes 1.5ns, and 7 cycles (for CAS 7) would take 10.5 ns. 10ns is less time than 10.5ns, so the DDR3-1600 CAS 8 has less latency time tha DDR3-1333 CAS 7. Here's where it gets easy:

1600/8*7=1400. DDR3-1400 would have the same latency time as DDR3-1600 CAS 8. DDR3-1333 CAS 7 is always slower.

1600/8*6=1200. DDR3-1200 would have the same latency time as DDR3-1600 CAS 8. Therefore, DDR3-1333 CAS 6 would have less response time than DDR3-1600 (better performance) but less bandwidth (less performance) and the actual performance would be determined by whether the program responds better to speed or quickness.
December 2, 2009 9:21:04 AM

Everything Thomas said is correct and well put, but remember the difference in performance is so small, and it appears mostly in benchmarks..So your ral life experience won't differ, unless you are an OCer, the 1600mhz then can give you more OCing headroom, or so I read, I don't own a core i5 or i7 yet !..
December 2, 2009 5:14:28 PM

Crashman said:


DDR3-1600 runs at 800 MHz, so CAS 8 takes eight 800 MHz cycles. An 800 MHz cycle happens in 1.25ns, so 8 cycles is 10ns. DDR3-1333 runs at 667 MHz, so a cycle takes 1.5ns, and 7 cycles (for CAS 7) would take 10.5 ns. 10ns is less time than 10.5ns, so the DDR3-1600 CAS 8 has less latency time tha DDR3-1333 CAS 7. Here's where it gets easy:

1600/8*7=1400. DDR3-1400 would have the same latency time as DDR3-1600 CAS 8. DDR3-1333 CAS 7 is always slower.

1600/8*6=1200. DDR3-1200 would have the same latency time as DDR3-1600 CAS 8. Therefore, DDR3-1333 CAS 6 would have less response time than DDR3-1600 (better performance) but less bandwidth (less performance) and the actual performance would be determined by whether the program responds better to speed or quickness.


And I used to think ram was just...... ram.

Thanks for that. So the ddr3 1600 cl7 are 8.75ns, which as you say is very good. Are they worth the extra $20?

Now here's where I got lost again. there's ddr3 1600 7-7-7-20, 7-7-7-24, 7-8-7-24, among many others. These three types are about $25 apart. What do these numbers actually mean and how do they affect performance?

One more thing, what role does voltage play?

AAAND one more other thing, when overclocking a cpu, will/must the ram be overclocked as well?

Thanks for the help guys. Much appreciated!
a b } Memory
December 2, 2009 8:11:28 PM

miatchapalooza said:
And I used to think ram was just...... ram.

Thanks for that. So the ddr3 1600 cl7 are 8.75ns, which as you say is very good. Are they worth the extra $20?

Now here's where I got lost again. there's ddr3 1600 7-7-7-20, 7-7-7-24, 7-8-7-24, among many others. These three types are about $25 apart. What do these numbers actually mean and how do they affect performance?

One more thing, what role does voltage play?

AAAND one more other thing, when overclocking a cpu, will/must the ram be overclocked as well?

Thanks for the help guys. Much appreciated!


I could explain, but it would take forever, have you tried googling an article on memory timings? Generally speaking those four numbers are in the order of performance for performance (tCL tRCD tRP tRAS) and, as the last guy said, the performance differences are usually noticeable only if you use a synthetic benchmark to point them out.

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a b } Memory
December 3, 2009 2:54:52 AM
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I already gave you a link about RAM timings read that. Its neatly given!
December 3, 2009 3:33:22 AM

hell_storm2004 said:
I already gave you a link about RAM timings read that. Its neatly given!


That's right! Forgot about that
December 7, 2009 2:50:16 PM

miatchapalooza said:
well it's not about the budget. the price of the 1600 is about $4 more than the 1333 here!

So 2000mhz is pointless if the highest spec is 1600? Im still confused!

Back to reading!



Glad you found the direction :)  Just to clarify yr confusion and probably other ppl.

here comes inside baseball @

RAM specs are agreed by an industry engineering group call JEDEC.

JEDEC official DDR3 speed is up to 1600.

there r 2 makers - the 1 that make DRAM Chips and another that make sticks of RAM that we use.

* DRAM chips technologies continuously improves. RAMs in shop now are built with chips from months ago. New chips that will be coming out will be "better" in terms of signalling quality, so they probably get classified at higher speed.

* Each batch of DRAM chips are specified to perform at an optimal speed say 1333MHz. RAM stick makers buys these chips & put them onto a stick and classify them as a DDR3 1333MHz 2GB. That is what i mean by "according to optimal spec."

* RAM market is extremely competitive. So RAM makers always try to out do each other, sometimes overclocking those 1333MHz DRAM chips to perform at 1600MHz on the stick. Now that is not an optimal specified speed for those DRAM chips. The reason they do this 1-Faster chips cost too much, 2-Quantity too low or 3-Faster chips not available yet.

As an example,

those DDR3 2000MHz RAM are a special breed b'cos they came from DRAM chips manufacturing batch of normally expected to perform at 1600Mhz, but their improved batch quality allows them to safely OC with additional proper engineering on the stick. The requirements r higher voltage to improve signalling at higher frequency, slower CAS Latency to prevent signals head-butt'g each other & a few more.

This is interesting b'cos

U could tone down DDR3 2000Mhz CL8 ram to perform at 1600MHz say at CL7 or maybe even CL6, who knows......

but IMHO not exactly worth the time and money b'cos, sometimes the rest of the system like the board just can't cope with it.

So, u c 2000MHz is not exactly pointless if u have the right board to go with it.
!