Which DDR memory to match 1333mhz FSB intel cpu?

kcs_tec
kcs_tec used Ask the Experts™
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Hey guys, here's a pretty straight-forward question for you:

I have a motherboard:  asus P5N32-E-SLI
which purports to support upto 1333mhz fsb

I'm upgrade my processor to: Core 2 Duo E8400 3GHZ 6MB Cache 1333Mhz CPU
(or alternatively to: Intel Core 2 Duo E7600 3.06GHz  1066Mhz 3MB Cache)

Question: I need to know which fast memory to buy which best suits my processor.
for example:

OCZ 4GB (2x2GB) DDR2 1150MHz/PC2-9200 Reaper Memory Kit CL5 2.2V (5-6-6-18)
Kingston 4gb Ddr2 1150mhz Hyperx Memory Non-ecc Cl5(5-5-5-15)
Kingston 4GB (2x2GB) DDR2 1066MHz/PC2-8500 HyperX T1 kit CL5 2.2V CL5(5-5-5-15)
Corsair 4GB (2x2GB) DDR2 1066MHz/PC2-8500 Dominator Memory Kit CL5(5-5-5-15)

Assuming the price is equivalent for both variants, could someone please recommend whether it's better to have a CPU and memory both operating at FSB 1066, or whether it's faster to use a CPU rated at 1333 fsb using 1150 fsb memory...?  

If anyone has the same motherboard as me, could they please confirm if they ever got 1066 or 1150 mhz mem to work on it, how they did it and which brand/model mem they used. Because I'm worried about this - a lot of people in the forums have reported huge problems with this model mboard and getting it to work at more than 800mhz fsb.

Thanks very much for any help guys!!

PS: Please please do NOT post random small comments with yes/no answers or post links to searches done on google for answers to my question.  thankyou.
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Top Expert 2012

Commented:
Don't bother with anything faster than DDR2-800 unless you are overclocking the FSB, because 800 is capable of supporting an Intel FSB 1600 cpu. The reason is Intel "quad-pumps" their FSB internally, so a 1600 FSB cpu actually uses a 400 FSB on the motherboard. DDR2 doubles the data rate on the motherboard, which means DDR2-800 running on a 400 FSB motherboard FSB is good enough, certainly for 1333 FSB cpus.  I hope these different FSB speeds do not confuse you, because it helps to know which FSB one is referring to.

For the memory you listed, they are all the same in timings except for the OCZ, which is slightly slower.  The 1150 rated RAM won't help unless you are overclocking, so at 800 the last three look the same.
Gary CaseRetired
Most Valuable Expert 2013
Top Expert 2009

Commented:
Agree -- DDR2-800 is fine.    I have both an E8400 and an E8500 systems, and use DDR2-800 with both.    Note also that if you use faster RAM you will likely need to change the RAM voltage settings in the BIOS, as most faster modules require non-standard voltages (above the standard 1.8v).

Commented:
Agree - Agree
Also note that the highest Official Standard is DDR2-1066.
Anything advertised as faster is not following an Industry Standard which can lead to compatibility issues.
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Author

Commented:
Wow, thanks for the help guys! I really didn't realise that that was the case wih ram (I'm a bit out of touch with the memory scene these days).

One more question please:

Is it worth just sticking with my current ram and trying to overclock that to mach the higher fsb of the new cpu I will buy?
(currently have a pair of standard 1gb Samsung DDR2 memory sticks in my computer (I guess running at some standard timings such 5-5-5-x).

I assume that the new DDR3 memory is a different pin-layout and would require a totally new MB..

Cheers,

-Seth
Top Expert 2012
Commented:
What we're trying to say is DDR2-800 already matches a 1600 FSB cpu and will match a 1333 FSB cpu.  A 1333 FSB cpu uses a 333 motherboard FSB (1333/4 for quad-pumped cpus) and will work fine with DDR2-667 RAM.  You don't have to overclock the RAM to make it work in the standard settings; it's only if you want to "push" your RAM and overclock it to squeeze every bit of performance from it, which I don't think is worth it for the trouble you need to go through.  If you currently have DDR2-667 or DDR2-800, there's no need to buy new memory to work with an E8400 or E7600.

I will note that many motherboards created before the introduction of the Wolfdales (45nm cpus) won't work with them, though they have the right socket and FSB settings.  At the very least, they require a BIOS update, and yours seems to require a 1403 BIOS: http://www.tomshardware.com/forum/247720-30-asus-p5n32-dont-e8400 and http://www.anandtech.com/showdoc.aspx?i=3138&p=2

DDR3 requires different slots and hence a different motherboard.

Author

Commented:
Thats great news!  Thanks guys for the clear, understandable answers to my questions. I think that I have all the answers I need now to go ahead and sort out my rig with a new cpu.
Cheers!! :)

Commented:
Check on the mother boards website manufacturer model if it supports DDR3 1333 Mhz so you get the maximum power on your PC

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