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667MHz and 800MHz

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January 1, 2008 11:21:37 AM

Hello guys i have 2GB 667MHZ DDR2 rams if i buy another 2GB but with 800MHZ so those 2 rams will fit?
btw 667MHz , 800MHz makes huge sence?

More about : 667mhz 800mhz

a b } Memory
January 1, 2008 12:17:47 PM

As far as I remember the 800mHz RAM will match the speed of the slowest RAM installed, IIRC. If I were you I'd get 2 x 2 gigs of DDR2 800mHz and sell your 667mHz stuff since DDR2 right now is cheap. Is this for a AMD system or a Intel system?
Do you have an OS that can see all of the DDR2 (4 gigs)? If you don't have a 64 bit OS, like XP64 or Vista 64, you won't be able to fully utilize all 4 gigs. I think you'll only be able to use 3-3.5 gig's of memory, IIRC.
January 1, 2008 12:46:21 PM

What you must look at first is if your mobo will support the 800. It may let you pop it in, it may even gladly accept it, it may even tell you that you are running PC-6400. The thing you must look at first is will it actually run at 800MHz. Many mobos now days accept ram that have the capability to run at high rates but limit them.

So if your mobo docs say that it will run ram at 800MHz, then the difference would be ram that has a data rate of about 15 to 16 GB per second compared to about 12 or 13. Depending on the CAS timings of the original RAM. Note that some good 5300 may be faster than some cheap 6400.

Benchmark the 667. See what you get. Then figure that equal timing ram at the 800 will get about 10 to 15 % better if your mobo will support it.
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January 1, 2008 1:53:52 PM

lunyone - my processor Intel dual core 2.66MHz i can give u further information about my pcs bcoz i know basically nothing about computers :x
January 3, 2008 3:24:45 AM

How exaclty can you tell if your MB will run at 800MHz? I have a Dell Inspiron 530S with 3GB RAM @ 667MHz. I was planning on replacing and adding more RAM. But, if i can't run it at 800MHz, then i'll stay put.

Sorry, didn't mean to hijack this thread!!!
January 3, 2008 5:01:13 AM

Look in your owner's manual under specifications.
January 3, 2008 7:24:20 PM

Mondoman said:
It's not normally a motherboard issue, but rather what info the RAM module maker programs into the onboard SPD. This post may clarify: http://www.tomshardware.com/forum/200599-30-memory-nooo...

To further clarify, when dealing with an oem system and an oem mobo you have to check in your manual.
ultimatefighter, you stated:
"How exaclty can you tell if your MB will run at 800MHz? I have a Dell Inspiron 530S with 3GB RAM @ 667MHz. I was planning on replacing and adding more RAM. But, if i can't run it at 800MHz, then i'll stay put."

http://support.dell.com/support/edocs/systems/insp530s/...
Memory
Type
667-MHz, 800-MHz DDR2 SDRAM
Memory connectors
four
Memory capacities
512 MB, 1 GB or 2 GB
Maximum memory
4 GB

no it would be a waste of $

January 5, 2008 5:08:20 PM

for example i have Kingston rams 2GB 667MHz if i buy another 2GB rams 667MHz but not Kingston does they fit?
Or i have to buy exact the same rams?:<
January 7, 2008 6:09:20 AM

ahh guys, i have the some problem...

well my mobo can run 800mhz, but how much of a performance increase will i get from 667 - 800?
January 7, 2008 7:41:04 AM

If your gaming you want see much difference in performance, a 32bit OS can only use 3GB of Ram. Also DDR2 667MHz Ram run at about 1.8 volts when some DDR2 800MHz runs at 2.1-2.2 volts and if your mobo can't push 2.2 volts your new Ram won't work. My Crucial Ballistix won't run below 2.1 volts, so your mobo might not be able to run them.
January 7, 2008 7:41:42 AM

wh3resmycar said:
ahh guys, i have the some problem...

well my mobo can run 800mhz, but how much of a performance increase will i get from 667 - 800?


Not much at all, if your looking for more performance then your looking in the wrong place.
January 7, 2008 12:47:31 PM

performance from DDR2 800 is negligible from 667

as you increase the memory rate u do get a small increase in performance however, once you reach the same memory clock rate as the FSB clock rate, increasing the memory clock rate gives you diminishing returns, esp when u take into account the cost of faster memory.

Just choose a memory wwith the same clock rate as the FSB of the CPU.

Latest Core2Duo chips have FSB of 1333MHz. Important thing to know is that it is quad-clocked data rate, meaning the actual FSB clock speed is only one quarter of the data rate.
The new QX9650 has a FSB clock speed of 333MHz which is a quarter of its 1,333MHz FSB data rate.

So DDR2 667 is more than adequate for the latest Intel processor. and any other processor out the as a matter of fact as it matches the FSB clock speed because DDR2 667 has an actual clock speed of 333 give or take a MHz.

Choosing memory faster than 667 means data can be ready sooner but it does NOT translate into huge speed gains AT ALL.
January 13, 2008 6:26:27 AM

systemlord said:
If your gaming you want see much difference in performance, a 32bit OS can only use 3GB of Ram. Also DDR2 667MHz Ram run at about 1.8 volts when some DDR2 800MHz runs at 2.1-2.2 volts and if your mobo can't push 2.2 volts your new Ram won't work. My Crucial Ballistix won't run below 2.1 volts, so your mobo might not be able to run them.



Thats not true. DDR2 800 can run (and per DDR2 spec it does run) on 1.8v just like 667. All DDR2 "runs" at 1.8v. Many manufactures like Crucial, will sell its higher end ram, like Ballistix, with SPD at a higher voltage to support lower timings, usually resulting in faster ram.

http://www.crucial.com/store/listmodule/DDRII/~HS~/list.html

CT12864AA800 DDR2 PC2-6400 • CL=6 • Unbuffered • NON-ECC • DDR2-800 • 1.8V • 128Meg x 64
and
BL12864AA804 DDR2 PC2-6400 • 4-4-4-12 • Unbuffered • NON-ECC • DDR2-800 • 2.2V • SLI-Ready • 128Meg x 64

Crucial just lowers the timings (to 4) and ups the voltage (to 2.2). These two sticks could be exactly the same with just a heat spreader on the ballistix or they could be using better chips on the ballistix where the non-ballistix wouldn't be stable at those timings. (I would have shown you 2gb sticks but for some reason they did not have the 2gb sticks of ballistix listed.) I bet dollars to donuts that you can run either stick at the others timings.

But to answer the original question, you can use DDR2 800 but it would mean either underclocking it to 667 or overclocking the 667 so all your ram runs at 800. You can not have memory working at different speeds but you can have different speced memory all running at the same speed (usually the lowest).

A word of warning, while it is unlikely, you may still run into problems by using diffent speed rams. For example the 800 stick's SPD may not have an option for the lower speed. This would result in you having to go into your bios and set the speeds yourself. If that sounds intimidating just buy the 667, and buy the same type you allready owned. That or replace all the ram with a new set of 800. The prices are about the same and you should obtain a small performance increase from the higher speed, though nothing you would be able to see. More total ram (as opposed to just faster ram) should give you a noticable improvement (up to 4gb with a 32 bit OS).

Hope that helped

One last thing - the ballistix stick costs $50 while the non ballistix is $27. If you are not overclocking then you may want to take the $26 and spend it elsewhere, unless you really want the yellow spreaders.

edit to bold the timings and voltage
January 13, 2008 3:06:44 PM

loosscru said:
Thats not true. DDR2 800 can run (and per DDR2 spec it does run) on 1.8v just like 667. All DDR2 "runs" at 1.8v.

It is true in my case, my Crucial Ballistix Tracers will not run at 1.8v with any timings. It will run at 2.0v at CAS 5 latency though.
Quote:
More total ram as opposed to just faster ram should give you a noticable improvement up to 4gb with a 32 bit OS.


I would like to see some links that shows 4GB of RAM gives a noticable improvement in performance, please. :)  If there is a noticable difference then I'll get 2 more GB of RAM.
January 14, 2008 11:50:07 PM

I guess I over generalized. Depending on your OS and what programs you generally run more ram can make a difference. Under vista with lots of memory intensive aps (photo editing or certain games, etc...) 2gb more memory would definitely help. If you are running a XP and just use word and an internet browser then 2gb would be fine (1gb would probably be fine) and another 2gb of ram would not have a noticeable effect.

It seemed like the original poster already decided that more ram was needed and I will not attempt to contradict them. Instead it is more of a question of what ram to run. As 667 and 800 prices are about the same, s1ckz can easily buy two 1gb sticks of 800 and underclock them. Shouldn't be a problem and it can be done for around $50. (does he need them, will he get the full performance, is s1ckz even a "he", didn't ask so it doesn't matter)

Systemlord- as far as your tracers are concerned they probably can run at 1.8 if you loosened the timings to where the non balistixs are set. Balistixs are just a better bin of the same stuff, so it would make sense that they could underclock to a lower bin. The balistixs usually overclock better then the vanilla crucial's as crucial is micron and they likely do not overbin their ram like other name brands.
Anonymous
a b } Memory
April 8, 2010 6:10:36 AM

hello, i got aspire acer 5050. i know my laptop can support 533/667 only. what if i put 800 type, anything bad happen or just the system detect 667 only?
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