Quicky question

[BaldEagl]

I've been working at putting together a parts list for a new machine, which I will build (if I can find a way to afford it) but, I have a quick question regarding RAM.

The Mobo I want accepts DDR2 1200 DDRAM.  the DDR2 DDRAM seems expensive compared to others, and there's not a lot of choice available.  Can I get away with DDR2 800 DDRAM until there's more choice and lower prices?  I'm guessing I can but not 100% sure.

[Krusty]

Most motherboards carry a range of supported frequencies. However, they usually have a lower limit.

Considering that DDR2 800 is still pretty fast these days, and that DDR2 1200 is almost nonexistent, I think it's safe to say DDR2 800 is supported.



That's 99% sure. To be 100% I'd check the specs based on what motherboard you have in mind. Which is it?

[humble]

There are a number of articles on matching memory speed to CPU for best performance however 800 memory will certainly to a good job regardless...difference will be pretty minimal in normal use/build...

[BaldEagl]

It's the new EVGA 132-CK-NF78-A1 LGA 775 NVIDIA nForce 780i SLI ATX Intel Motherboard.

[Krusty]

It'll run 800 just fine.

"Maximum of 8GB of DDR2 533/667/800/1200MHz SLI-Ready memory"


( link here )

[BaldEagl]

Great.  Thanks.

[MrRiplEy[H]]

Find out which type of ram your CPU requires and use that. No benefit whatsoever going over that unless you plan to FSB overclock the box.

[BaldEagl]

Originally posted by MrRiplEy[H]
Find out which type of ram your CPU requires and use that. No benefit whatsoever going over that unless you plan to FSB overclock the box.

How do you find that out?  Here's the processor I'm looking at:

Intel Core 2 Duo E6750 Conroe 2.66GHz 4M shared L2 Cache LGA 775 65W Dual-Core Processor 1333 FSB

[Krusty]

Best not to undercut yourself either.


800MHz FSB was the rage until Conroe chips came out. I went and got a new 1066MHz FSB chip and love it, but if I'd waited 3-4 months I'd have gotten a 1333 MHz FSB chip instead. Don't get 533MHz chips because your CPU runs at (2x) 513. Get the ram that will last through future upgrades. You can always underclock it if you really want to.

Oh, and having 533MHz ram vs 800mhz ram doesn't give you very much of a benefit on a 1033 FSB chip. The theoretical advantage is that the ram's timing matches the CPU's FSB, so it doesn't have to "wait" -- well the 800 mHz is faster than the CPU's FSB so there are more chances of hitting the window for read/write, more opportunity to hit a window (there are more windows), so the odd chance of running into a blocked window of opportunity (to read/write) is pretty small. In general.

[BaldEagl]

Originally posted by Krusty
Best not to undercut yourself either.


800MHz FSB was the rage until Conroe chips came out. I went and got a new 1066MHz FSB chip and love it, but if I'd waited 3-4 months I'd have gotten a 1333 MHz FSB chip instead. Don't get 533MHz chips because your CPU runs at (2x) 513. Get the ram that will last through future upgrades. You can always underclock it if you really want to.

Oh, and having 533MHz ram vs 800mhz ram doesn't give you very much of a benefit on a 1033 FSB chip. The theoretical advantage is that the ram's timing matches the CPU's FSB, so it doesn't have to "wait" -- well the 800 mHz is faster than the CPU's FSB so there are more chances of hitting the window for read/write, more opportunity to hit a window (there are more windows), so the odd chance of running into a blocked window of opportunity (to read/write) is pretty small. In general.

Huh?

Not sure that answered my question;


quote:
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Originally posted by MrRiplEy[H]
Find out which type of ram your CPU requires and use that. No benefit whatsoever going over that unless you plan to FSB overclock the box.
--------------------------------------------------------------------------------



How do you find that out? Here's the processor I'm looking at:

Intel Core 2 Duo E6750 Conroe 2.66GHz 4M shared L2 Cache LGA 775 65W Dual-Core Processor 1333 FSB

[Krusty]

Your CPU has a FSB of 1333MHz, so you'd want your DDR2 to be at half that, or 666MHz. If you get 800MHz DDR2, you can run it stock or clock it down to 666 (if your motherboard supports this!! Mine doesn't!)

[MrRiplEy[H]]

Usually the motherboards default to the 'stock' memory speed meaning your 800 ram will run at 667Mhz if your processor requires that. Only manually you can run at 'asynch' settings where ram runs faster than cpu fsb. This generally doesn't provide any speed benefits however, in fact the opposite has been found.

IIRC with quad core it was found that it's better to 'overclock' ram to reduce the effect of the quad-cpu bottleneck but with normal cpu's stock is what you should set.

Intel cpu's use 'quad pumped' fbs meaning the reported fsb is four times the actual cpu fsb. Giving that DDR2 ram runs at twice the FSB speed you have to divide the intel reported FSB by 2 to get the correct ram speed.

So you'll do fine with 667Mhz but since 800mhz comes virtually at same price it doesn't hurt to get 2-4 gigs of that. More important is memory timings (the number with 12-5-5- etc. there lower is better).

[BaldEagl]

So what you're saying is that anything over 667 won't be used anyway right?  So why do they even make 1333 PC3 DDRAM (or 1200 PC2 DDRAM for that matter)?  Overclocking?  But who could overclock their FSB to 2666 (or even 2400)?

Anyway, this then raises another question.  There are both PC2 5300 and PC2 5400 chips available in 667 Mhz DDRAM.  Does it matter which I use?  I can't find anything on it on the EVGA (mobo) website (or anywhere alse for that matter).  Given similar pricing, is the 667 better to use than the 800?

[EDIT]  Just saw MrRiplEy[H]'s post after typing this but a few of my questions are still open.

[EDIT2]  Guess my quicky question got longer than I thought it would be

[Krusty]

Okay, I'll answer all your questions:


Get the 800MHz ram.

[Fulmar]

Originally posted by BaldEagl
So what you're saying is that anything over 667 won't be used anyway right?  So why do they even make 1333 PC3 DDRAM (or 1200 PC2 DDRAM for that matter)?  Overclocking?  But who could overclock their FSB to 2666 (or even 2400)?

Anyway, this then raises another question.  There are both PC2 5300 and PC2 5400 chips available in 667 Mhz DDRAM.  Does it matter which I use?  I can't find anything on it on the EVGA (mobo) website (or anywhere alse for that matter).  Given similar pricing, is the 667 better to use than the 800?

#1 For the DDR3 setups, you have to remember that the FSB's of Intel processors are quad pumped*.  So that 1333mhz FSB E6850 or whatever, divided by 4* = ~ 333hz.  So DDR2 at 667mhz (2 x 333mhz) will equate to a 1:1 FSB to RAM ratio which is ideal.  DDR3 at 1333mhz divided by 3 = ~444mhz.  So DDR3 setups are really only going to gain you a large benefit if you are A) overclocking or B) waiting for a faster FSB CPU from the future that has a FSB of 1666mhz ( divided by 4 = ~ 417mhz) where a 1:1 ratio will work at stock.

But DDR3 is uber expensive and should only be used if you have a wad of cash you want to waste and make your Johnson E-Rod longer.

There are plenty of people that overclock their CPU's to insane speeds just as someone wants to crank out that extra horsepower in their '87 Camaro.  Not my cup of tea, but hey....

#2 PC5300 is DDR2 running at 667mhz, PC5400 runs at 675mhz.  No real performance gain.  I'm not sure why they manufactured PC5400.

#3  As for 667mhz compared to 800mhz - I would spend the extra $2-5 per 2gb on the 800mhz for 2 reasons.  1)  Allowed for future overclocking if you desire.  2)  A little more future-proof for faster FSB CPU's; however, to my knowledge there are no CPU's or motherboards out as of current that support a FSB of 1667mhz.