Computer memory question

I am slightly computer literate but in the dark on much. I am looking to upgrade memory on my Gateway laptop, it runs ddr2 sodimm. What I'm not clear on is the difference between ram speeds and designation as PC(2) 4200 or 4300 and such? I'm trying to buy memory on ebay and have bid on something that should work, 533mhz and PC2 4200. Does it need to be 4200 or can it run 4300? I don't even know what this shit means. When I go to gateway support and run the activeX on my system it tells me I am running 4300 however when I phone tech support and give my serial number they swear I have 4200. Sometimes I see PC, sometimes PC2. I'm going to shut down and physically see what is in here but I'd like to know if it really even matters.

Thanks for the help..... I bow down to your geekdom.

you can go here
http://www.crucial.com/
they have a system scanner as well as a select your computer form to find what memory your system needs.

the general rule of thumb is as long as you are in the same generation (DDR2), you can use memory that is faster than that which is already in your machine. so if you have 4200, 4300 should work.

If you know what key to hit on startup, you can enter the bios, and it should let you know what clockspeed your memory is running at. Gateway probably has the key listed somewhere, but it in my experience its either DEL, F1, or F2. Depending on the system, hitting Tab may give you a more detailed system post. None of this really matters.

If gateway swears they put PC2-4200 in there, it's most likely true. Regardless, you should be able to get just about any DDR2 so-dimm module working without a problem. Higher frequency and lower latency is generally better, but it really doesn't really matter in your case. Buy something cheap spec'd at 4200/4300 (or whatever the equivalent is in clockspeed is), and you'll be fine.

Thanks guys. So the 4200 actually is a speed reference. The 533 being clockspeed I guess. If I don't get my first one I can get one that is referred to as pc4200.... I take it no problem there? Still DDr2 and dosimm 200 pin etc. Not sure what the lower latency reference is too. Hopefully I'll get my first choice and I'm sure it will work.

The memory actually reads PC2 4200-3-444-12 and somewhere it said 533mhz.

You're correct, DDR2-XXX is the clock speed (in your case 533). PC-XXXX is the theoretical bandwith (tranfers /s x 8 bytes /s). Most manufacturers round this down to 4200; others claim they actually get faster transfer times and round up to 4300. I doubt you will actually be able to tell the difference, and they both should work.

Things to remember for memory upgrades. (These are generalizations and may not apply to every system out there 100% but a large majority):

DDR2 requires matched pairs - of the same size and speed memory chips to be installed at a time (a few notebooks this does not apply too)

You are usually safe if you get a higher speed memory module and run it in a slower computer. They step down the majority of the time.

The numbers you ask about are 2 ways of saying the same thing. IE DDR2-533 is the same as PC2-4200 memory speed- just different ways to confuse computer jongs, DDR2-667 are PC2-5300, DDR2 started at 400 mhz, and goes up 533, 667, 800, etc.

The number of pins is very important- they design the chips so they fit the socket and if you order the wrong style (especially on an Ebay bid without a return policy) then you are screwed.

Many generic chips should work fine- the name brand companies (HP, Dell, IBM, etc.) will tell you you need to order based on their part numbers, but most times generic memory works fine, if in doubt ask the memory vendor or store before you purchase and find out their return policy. Only a few systems today require special part numbered memory modules, and they tend to run higher in price for these modules. You do gain one added benefit, they have tested the memory in that specific computer model and usually warrant and guarantee compatibility and have many times an installation manual for that specific computer to install the memory.

You can read through things like the Kingston Ultimate Memory guide (on Kingston.com) for more info. A site that specifically talks about the DDR2 memory is this link:

http://www.simmtester.com/page/news/...ws.asp?num=109

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DDR2 requires matched pairs - of the same size and speed memory chips to be installed at a time (a few notebooks this does not apply too)

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DDR2 does not require matched pairs by default. Matching is recommended when dual channel is being used, but flexibility in this area varies greatly depending upon the memory controller.

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The number of pins is very important- they design the chips so they fit the socket and if you order the wrong style (especially on an Ebay bid without a return policy) then you are screwed.

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This has been covered. If you buy a DDR2 so-dimm module, you should be fine.

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Originally Posted by trickflip

DDR2 does not require matched pairs by default. Matching is recommended when dual channel is being used, but flexibility in this area varies greatly depending upon the memory controller.



This has been covered. If you buy a DDR2 so-dimm module, you should be fine.

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Directly from the Crucial FAQ's:

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If you have a dual-channel platform and you want to take advantage of the performance gain it offers, our advice is to simply purchase your DDR or DDR2 memory in pairs. However, be very careful to order two modules with the exact same specifications; the modules must be identical to each other to perform correctly.

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The DDR and DDR2 sockets on laptops are the same number of pins, but different voltages- so they notch the chips differently to avoid damaging by mistakenly getting a DDR module for a system that requires DDR2 memory...

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If you have a dual-channel platform and you want to take advantage of the performance gain it offers, our advice is to simply purchase your DDR or DDR2 memory in pairs. However, be very careful to order two modules with the exact same specifications; the modules must be identical to each other to perform correctly.

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This differs from what I stated very slightly, and is not completely true. Some dual channel memory controllers allow for differences, not to mention that a module can almost always run at timings lower than what it is specified for. This is all granted his laptop is running dual channel anyway.

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The DDR and DDR2 sockets on laptops are the same number of pins, but different voltages- so they notch the chips differently to avoid damaging by mistakenly getting a DDR module for a system that requires DDR2 memory...

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Stating the obvious? I don't think he is going to buy memory that is not listed as DDR2.

Well I won a bid, seems like the right stuff now I just need to get the guy accepting paypal. Power seller but didn't list paypal as an option and I missed that. Slow unprotected headache otherwise but he will accept paypal if I cover his fees which I would think is against the user agreement. That's minor. Thanks for the help. I 'think' I'm good on the unmatched pair. In fact gateway somewhere stated I could use faster on one channel just that it would default to the lower speed. I hope the same goes for size of memory. I ran (still run) two different memories in my old machine, a 256 and a 128.

Good thing I asked here (font of all knowledge) because there's a lot of little shit to watch for and they don't make it easy. I got DDR2 533 sodimm in 1 gig made by HP. Hope that covers it.