# How do I determine memory modules I can use for my computer?
**URL:** https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492
**Category:** Factual Questions
**Created:** [August 12, 2006, 10:10pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492 "2006-08-12T22:10:03Z")
**Posts on this page:** 19
**Page:** 1
### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 12, 2006, 10:10pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/1 "2006-08-12T22:10:03Z")
As a long-time PC user and computer professional, I’m somewhat ashamed to realize I do not know how to determine what memory modules my PC can and cannot use. I’d like to upgrade my memory from 512mb to at least 1GB, maybe two.
Running SiSoftware Sandra, a diagnostic program, I see that I currently have the following:
System Memory Controller
Location : Mainboard
Error Correction Capability : None
Number of Memory Slots : 2
Maximum Installable Memory : 2GB
Bank 1 - DIMM1 : Hyundai Electronics HYMD132 645A8-H 21470771 DIMM Synchronous DDR-SDRAM 256MB/64 @ 266Mt/s
Bank 2 - DIMM2 : Hyundai Electronics HYMD132 645A8-H 21330771 DIMM Synchronous DDR-SDRAM 256MB/64 @ 266Mt/s
So, as a 1st step, I think I’ll replace one of the 256MB modules with 1GB. But what type? How much does it have to match what I already have? Does it have to be DIMM? Does it have it to be Synchronous DDR-SDRAM? What kind of leeway do I have here?
From some Googling I see there are different DIMMS with different amounts of pins. Do I care about the number of pins, or does that not matter because that’s the connection between the chips and the module, and not the module to the PC?
This is an aging machine, I don’t need the fastest memory out there or anything special. I’m just trying to extend it’s useful life a bit.
Thanks for any help that can be offered.
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 12, 2006, 10:15pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/2 "2006-08-12T22:15:24Z")
Oh, and any suggestions as to a place to get memory cheap is welcome, too.
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### Author:  [@Kinthalis](https://boards.straightdope.com/u/Kinthalis)
#### Post date: [August 12, 2006, 11:19pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/3 "2006-08-12T23:19:48Z")
I appears you need DDR SDRAM running at 133 mhz (266mhz) Or PC2100.
This type fo RAM is odl enough that it’s actually MORE expensive than the new, much faster stuff 🙂
Try new egg for a decent price.
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### Author:  [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)
#### Post date: [August 12, 2006, 11:25pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/4 "2006-08-12T23:25:32Z")
I’ve been using computers for some time. I’ve pretty much given up on trying to keep track of memory types and such. When I need to upgrade memory on a machine I usualy use the memory recomender things on [www.bestbuy.com](http://www.bestbuy.com) or [http://www.crucial.com/](http://www.crucial.com/) I’ve generaly found crucial has the best prices.
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 12, 2006, 11:26pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/5 "2006-08-12T23:26:02Z")
Thanks much!
Can you explain “133 mhz (266mhz)”? Is it something like running 133mhz on the bus, but twice that internally (or vice-versa)?
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 12, 2006, 11:27pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/6 "2006-08-12T23:27:54Z")
> [@boytyperanma](#):
>
> I’ve been using computers for some time. I’ve pretty much given up on trying to keep track of memory types and such. When I need to upgrade memory on a machine I usualy use the memory recomender things on [www.bestbuy.com](http://www.bestbuy.com) or [http://www.crucial.com/](http://www.crucial.com/) I’ve generaly found crucial has the best prices.
Thanks, I’ll check that out!
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### Author:  [@brianjedi](https://boards.straightdope.com/u/brianjedi)
#### Post date: [August 12, 2006, 11:30pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/7 "2006-08-12T23:30:00Z")
Use Crucial’s system selector to find what specs you need, then start comparing prices. Sometimes you can beat Crucial’s price.
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 12, 2006, 11:35pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/8 "2006-08-12T23:35:08Z")
OK, the [crucial.com](http://crucial.com) webiste recommended:
DDR PC2700 • CL=2.5 • UNBUFFERED • NON-ECC • DDR333 • 2.5V • 128Meg x 64
[http://www.crucial.com/store/MPartspecs.Asp?mtbpoid=57322550A5CA7304&WSMD=Presario+6000+Series+(Pentium+4+processors)&WSPN=CT523987](http://www.crucial.com/store/MPartspecs.Asp?mtbpoid=57322550A5CA7304&WSMD=Presario+6000+Series+%28Pentium+4+processors%29&WSPN=CT523987)
Sounds kinda different from from what you said, **Kinthalis** , what do you think?
Thanks again for the advice.
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### Author:  [@Kinthalis](https://boards.straightdope.com/u/Kinthalis)
#### Post date: [August 13, 2006, 12:07am UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/9 "2006-08-13T00:07:43Z")
> [@Revtim](#):
>
> OK, the [crucial.com](http://crucial.com) webiste recommended:
> DDR PC2700 • CL=2.5 • UNBUFFERED • NON-ECC • DDR333 • 2.5V • 128Meg x 64
> [http://www.crucial.com/store/MPartspecs.Asp?mtbpoid=57322550A5CA7304&WSMD=Presario+6000+Series+(Pentium+4+processors)&WSPN=CT523987](http://www.crucial.com/store/MPartspecs.Asp?mtbpoid=57322550A5CA7304&WSMD=Presario+6000+Series+%28Pentium+4+processors%29&WSPN=CT523987)
>
> Sounds kinda different from from what you said, **Kinthalis** , what do you think?
>
> Thanks again for the advice.
I’m not sure how Crucial’s website determines the type of RAM you needed. Did you specify: HP - Compaq Presario 6000 Series, is that your system? If so, and oyu haven’t changed the mobo or CPU, then I’d go with that. The RAM you currently have appears to be PC2100 given the model numbers you mentioned, but it is quite possible that your motherboard and CPU can run the memory Crucial mentions. So if that is indeed your system, then go with Crucial’s recommendation.
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### Author:  [@Jurph](https://boards.straightdope.com/u/Jurph)
#### Post date: [August 13, 2006, 12:45am UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/10 "2006-08-13T00:45:23Z")
Hey, **Revtim** , can you post more details about your computer? If you can tell us your motherboard make & model, or model number of the system if you got it from Dell or Gateway, or the motherboard chipset (e.g. “VIA KT-133” or “nVidia nForce 2”), we can definitely tell you how much RAM and what kind you can use.
You do need to know the number of pins, but that’s almost certain to be 184, and you don’t need to count them. All DDR SDRAM since about 2000 has been the 184-pin standard, and DDR SDRAM that uses the PCxx00 naming convention is always 184-pin. **Kinthalis** ’s point about PC2100 being more expensive is valid and has a neat side effect: you can install any 184-pin RAM rated for a higher speed and it should work in your system. That means that if your system is only rigged to run PC2100 RAM, but PC2700 is the cheapest 184-pin RAM out there, (which it currently is) you can still add it to your machine and run it at PC2100 speeds. You’ll be _underclocking_ your RAM, which means that if you want, you can set the latency timings very very low, shaving precious nanoseconds off every memory transfer. 😉
Newegg is amazing about customer service. On older hardware you’ll typically pay a 5-10% premium over the bargain-basement prices on Pricewatch and similar sites, but if you get bad RAM, good luck getting them to honor their warranty. I’ve had bad parts come from Newegg and gotten good parts with no hassle.
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 13, 2006, 12:48am UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/11 "2006-08-13T00:48:02Z")
> [@Kinthalis](#):
>
> I’m not sure how Crucial’s website determines the type of RAM you needed. Did you specify: HP - Compaq Presario 6000 Series, is that your system? If so, and oyu haven’t changed the mobo or CPU, then I’d go with that. The RAM you currently have appears to be PC2100 given the model numbers you mentioned, but it is quite possible that your motherboard and CPU can run the memory Crucial mentions. So if that is indeed your system, then go with Crucial’s recommendation.
It’s a Compaq Presario 6LPXE1; I did not see an entry for that particular model, so I chose the more general 6000. That brought my confidence level down a bit on its assessment.
FYI, the specs on Compaq website say:
> [@](#):
>
> System Memory:
> 128, 256, 512MB, 1.0GB 266MHz PC 2100 DDR DRAM
> • Max Capacity - 1.0GB
> • 2 DIMM slots (128, 256MB
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 13, 2006, 12:52am UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/12 "2006-08-13T00:52:26Z")
> [@Jurph](#):
>
> Hey, **Revtim** , can you post more details about your computer? If you can tell us your motherboard make & model, or model number of the system if you got it from Dell or Gateway, or the motherboard chipset (e.g. “VIA KT-133” or “nVidia nForce 2”), we can definitely tell you how much RAM and what kind you can use.
>
> You do need to know the number of pins, but that’s almost certain to be 184, and you don’t need to count them. All DDR SDRAM since about 2000 has been the 184-pin standard, and DDR SDRAM that uses the PCxx00 naming convention is always 184-pin. **Kinthalis** ’s point about PC2100 being more expensive is valid and has a neat side effect: you can install any 184-pin RAM rated for a higher speed and it should work in your system. That means that if your system is only rigged to run PC2100 RAM, but PC2700 is the cheapest 184-pin RAM out there, (which it currently is) you can still add it to your machine and run it at PC2100 speeds. You’ll be _underclocking_ your RAM, which means that if you want, you can set the latency timings very very low, shaving precious nanoseconds off every memory transfer. 😉
>
> Newegg is amazing about customer service. On older hardware you’ll typically pay a 5-10% premium over the bargain-basement prices on Pricewatch and similar sites, but if you get bad RAM, good luck getting them to honor their warranty. I’ve had bad parts come from Newegg and gotten good parts with no hassle.
You bet. From SiSoftware Sandra:
Mainboard Manufacturer : Compaq
MP Support : 1 Processor(s)
MPS Version : 1.40
Model : 07E8h
Serial Number : U221KN3ZA011
It’s a Compaq Presario 6LPXE1
Thanks again everybody for the advice.
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### Author:  [@Jurph](https://boards.straightdope.com/u/Jurph)
#### Post date: [August 13, 2006, 3:36pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/13 "2006-08-13T15:36:10Z")
**Revtim** , that seals it: your machine can take (almost) any [184-pin DDR SDRAM](http://en.wikipedia.org/wiki/DDR_SDRAM) – anything PC2100 or faster will run at your system’s maximum, which is 133MHz (or 266 if you count the doubling effect). DDR-333 (PC-2700) is the cheapest right now; it will run fine and even provide you a little cushion, since it will be running at 80% of its intended speed.
Enjoy!
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 14, 2006, 12:45pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/14 "2006-08-14T12:45:49Z")
Thanks much **Jurph**.
Can you describe how you figured that out? Is it simply that all PC-2700 can run in a machine that runs PC-2100?
Also, you say it can take “almost” any 184-pin DDR SDRAM, how do I know which will not?
Thanks again.
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### Author:  [@Jurph](https://boards.straightdope.com/u/Jurph)
#### Post date: [August 14, 2006, 3:57pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/15 "2006-08-14T15:57:29Z")
The Wikipedia article I linked to above goes into pretty good detail about how DDR SDRAM works. One of the most illuminating statements is this:
> [@](#):
>
> There is no architectural difference between DDR SDRAM designed for different clock frequencies, e.g. PC-1600 (designed to run at 100 MHz) and PC-2100 (designed to run at 133 MHz). The number simply designates the speed that the chip is guaranteed to run at. Hence you can run DDR SDRAM at lower clock speeds than it was made for (underclocking) or higher clock speeds than it was made for (overclocking).
Note, however, that they mention PC-1600 (aka DDR200, which operates at 100MHz). This is slower than your machine can handle, which is why I included the caveat “almost” – PC-1600 is the one type of 184-pin RAM that won’t run in your machine. As for figuring out what you could handle, I googled your machine’s model and the word ‘RAM’: [Google search for ‘Presario 6LPXE1 RAM’](http://www.google.com/search?hl=en&lr=&q=Presario+6LPXE1+RAM&btnG=Search). Looking around in the results, every one that mentions RAM mentions “PC-2100”. You’re right that the HP website isn’t terribly helpful. After poking around on Google, I discovered that the 6LPXE1 is a model number from the “[Presario 6000T](http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&cc=us&docname=bpb11702&product=94003&dlc=en&lang=en)” series, and that the 6000T takes PC-1600 or PC-2100 RAM.
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 14, 2006, 7:09pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/16 "2006-08-14T19:09:45Z")
Thanks again **Jurph** , I greatly appreciate it.
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### Author:  [@Jurph](https://boards.straightdope.com/u/Jurph)
#### Post date: [August 14, 2006, 7:22pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/17 "2006-08-14T19:22:33Z")
…so my guess about your machine not taking PC-1600 RAM was wrong. Your machine will run either PC-1600 or PC-2100, at their normal speeds, or any faster DDR at PC-2100 speeds. [This stick](http://www.newegg.com/Product/Product.asp?Item=N82E16820211131) of PC-2700 is cheaper than several of the PC-2100 sticks on offer, and should work fine. $87.00 plus shipping is not the lowest price you’ll find. You can do better with [these vendors](http://www.pricewatch.com/memory/4922-1.htm?System+Memory) on price for example, but _caveat emptor_. For premium-brand RAM with reputable service, you’ll probably pay more like $95 or $100. **drachilix** builds and repairs PCs for a living; he would know which brands flake out and which don’t.
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [August 14, 2006, 7:28pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/18 "2006-08-14T19:28:25Z")
If your machine is several year sold you may want to hold off on further investment. Going from 512 megs to 1 gig isn’t going to yiled any kind of noticable speed benefit for everyday stuff. If you’re doing heavy video rendering or intensive data transfer stuff it might be worthwhile, but the little perforamance bump isn’t going to knock your socks off.
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### Author:  [@Revtim](https://boards.straightdope.com/u/Revtim)
#### Post date: [August 14, 2006, 8:44pm UTC](https://boards.straightdope.com/t/how-do-i-determine-memory-modules-i-can-use-for-my-computer/368492/19 "2006-08-14T20:44:23Z")
> [@astro](#):
>
> If your machine is several year sold you may want to hold off on further investment. Going from 512 megs to 1 gig isn’t going to yiled any kind of noticable speed benefit for everyday stuff. If you’re doing heavy video rendering or intensive data transfer stuff it might be worthwhile, but the little perforamance bump isn’t going to knock your socks off.
Specifically, I want more memory to run virtual machines in VMWare (and maybe Virtual PC).