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.
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.
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.
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P35-DS3L l E8400 @ 3.6Ghz l OCZ Vendetta 2 l 4GB G.Skill 8000PQ@1000mhz 4:5 l WD3200AAKS 320GB l Evga 8800GTS 512 l Creative SB X-Fi Xtreme Music l Corsair HX520 l Antec Sonata III 500 l Vista Home Premium32 SP2 build 6002
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."
Message edited by kpo6969 on 01-03-2008 at 10:25:56 PM
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P35-DS3L l E8400 @ 3.6Ghz l OCZ Vendetta 2 l 4GB G.Skill 8000PQ@1000mhz 4:5 l WD3200AAKS 320GB l Evga 8800GTS 512 l Creative SB X-Fi Xtreme Music l Corsair HX520 l Antec Sonata III 500 l Vista Home Premium32 SP2 build 6002
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.
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.
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"Ah, yes, divorce, from the Latin word meaning to rip out a man's genitals through his wallet." - Robbin Williams
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.
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.
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.
Message edited by systemlord on 01-13-2008 at 06:07:38 PM
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Intel C2D E6600 @ 3.2GHz * Asus P5E * 2x1 GB Crucial Ballistix Tracers * Raptor X * EVGA Geforce 8800GTX 768MB 651MHz/1525MHz/2100MHz * X-FI Fatal1ty Pro * Enermax Infiniti 720W PSU * Creative THX5.1 * Tuniq Tower 120
Silverstone TJ09 * Windows XP
If there is a noticable difference then I'll get 2 more GB of RAM.