Can DDR2 800 CL5 Co-Exist With a DDR2 500 CL4?

I have a computer which currently uses one DDR2 800 1GB stick of ram. would it help if I added a DDR2 533 1gb stick? Would it even work? Thanks!
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Dave BaldwinFixer of ProblemsCommented:
If it works, it will run at the slower speed.
Would it help?  It depends on how much RAM you are currently using at the moment - if your programs are swapping to disk frequently, it would help a lot.  If your average memory usage is a lot less than 1GB, it won't help much, unless you are planning on using a program that is memory-intensive, such as Photoshop with large files.

The combination will cause your system to run the FSB no faster than 266.67 (doubling that, which DDR2 does, gives you 533). Slowing down to DDR2-533 may not be a drawback if your current cpu doesn't require an FSB faster than 266.67, such as the Intel Core Duo family which runs at 1066 (which is 4x 266.67, the way "quad-pumping" works).

It is also possible that the combination will not work at all, because some motherboards are very particular about what RAM you install.  Your motherboard manufacturer's website should specify what RAM is compatible with it.
Faisal KhanCommented:
It would work but there wont be any advantage you get out of it. it may keep your processor busy coz of two different bus speeds of RAM modules. If you really want to increase your ram try using htis website. it will scan your pc and advise you right memory for your PC.
hope this helps
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Gary CaseRetiredCommented:
Yes, it will work -- and it may not even cause any performance hit, depending on the other characteristics of your system.

As noted above, BOTH modules will run at DDR533 speeds if you install the 2nd module.    The latency difference between the original speed (800MHz) vs. the new speed (533MHz) is 7.5ns vs. 6.25ns ... so there will be a 16% increase in the CAS latency time.    HOWEVER, if you system supports dual channel access, then adding the 2nd module will also enable dual channel mode -- so the bandwidth of the actual data transfers will be notably faster than it was (not double, since it's only clocking at 67% of the original speed;  but nevertheless faster than it was.

The actual difference depends on a variety of factors -- but in general doubling your memory from 1 to 2 GB will improve your performance, regardless of the slower memory clocking.
i have found some motherboards to be picky about different Ram sticks
But i agree MOST do work
benj707Author Commented:
After I insert the DDR2 533 1gb stick, my monitor can no longer make a connection to my computer, I get the message "no signal". Any ideas?
Try each RAM stick separately.  If they work separately but not together, then they are not compatible.  This may be due to settings in the SPD chip in one that the other cannot run at.

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