View Full Version : PC memoery

02-11-2004, 16:12:42
OK both my recent PCs are a bit slow, sometimes I wait ages for it to do whatever it's doing in the background before I get a response. I suspect a memory boost might help out. So what's the general opinion on the minimum amount it's worth having these days ?

Neither PC seems to have good documentation with them. The Compaq Presario S3150 (http://www.morgan-auctions.co.uk/auction/lots.asp?LotID=29751) does at least admit to using DDR-SRAM on the label on the front of the case, but it's documentation seems only interested in telling you how to install a new module, not what the module should be.

The HP Pavilion 500 (http://www.morgan-auctions.co.uk/auction/lots.asp?LotID=29750), well I can't find the documentation for it, which is ludicrous since it can't have been slung. No idea why it isn't by the PC itself. But I assume it takes much the same sort of module. The only thing is that a Net search seems to suggest that different letters after the "500" results in different modules needed, which is very confusing.

Been a while since I got involved with this sort of thing.

Any advice / suggestions ? I'm thinking of getting something off ebay if I can work out for sure what is suitable.

Sir Penguin
02-11-2004, 19:52:35
Absolute minimum these days is 256 MB on a Windows XP box. Recommended is 512 MB.

Memory comes in two mutually exclusive types: SDR (Single Data Rate) and DDR (Double Data Rate). SDR is the old kind, usually labeled PC100 or PC133 or something like that. DDR is newer, and is labelled PC2100 or PC2700 or something like that. The big difference between SDR and DDR is that SDR sends one piece of data on each clock cycle, while DDR sends two (hence doubling the data rate! :gotit: ). For that reason, DDR modules are marketed as 266 MHz, 333 MHz, etc., despite the fact that they actually cycle at 133 MHz and 166 MHz like the old SDR modules. But anyway, that's irrelevant.

If you've got a DDR motherboard, then theoretically any DDR memory module will work fine in it. However, every RAM module and the CPU will be limited to the slowest. You might also have problems if your CPU has a faster front-side bus speed (labeled as FSB speed on motherboard and CPU descriptions) than the RAM speed, because then your computer might mistakenly run the memory way faster than it was intended for, which will probably keep the computer from booting.

It looks like any HP Pavilion 500 will accept up to 512 MB of PC133 RAM. The Compaq Presario S3150 will take either PC2100 (266MHz) or PC2700 (333 MHz), depending on the type. In either case, you can't go wrong with PC2700.

HP Pavilion 500 series: http://tinyurl.com/3jlal
Compaq Presario S3150 series: http://tinyurl.com/4ps6b

With both links, click the appropriate model number, then Product Information, then Product Specifications (or "How do I find my model number" if you don't know your model number).


02-11-2004, 21:01:12
SP, you are forgiven for all that "buyer doesn't need protection" stuff ;)

Thanks for the info, I'll go check it out immediately (well after a quick look in the Counterpoint area anyway :))

Sir Penguin
02-11-2004, 21:13:30
Hey, I never said that the buyer doesn't need protection. I said that the buyer is responsible for dealing with bad things from which he is not protected. Or, more succinctly, ignorance is not an excuse. Or, even more succinctly, buyer beware. ;)


02-11-2004, 21:18:23
That what I said.

02-11-2004, 22:03:24
Doncha just hate not being able to correct typos in the title ?

Anyway, that aside....

Typical apparently similar PCs need DIFFERENT upgrades.

HP Pavillion 6935 (http://www.crucial.com/store/listparts.asp?mfr=HP&cat=RAM&model=Pavilion+7935)
Presario S3150uk (http://www.crucial.com/systemscanner/viewscanbyid.asp?id=27451D9931D926C3)

One is PC133, the other PC2100 just as you mentioned. Not that I doubted it for a moment.

They both came with 256M so I guess doubling it should sort the delays out (hopefully). Now just gotta find the best deal.

Sir Penguin
02-11-2004, 22:38:02
God, PC133 RAM is expensive. Be sure not to get ECC or buffered or registered RAM.


02-11-2004, 23:04:43
Got a few ebay auctions been watched in "my ebay" at the moment. Looks very easy to pick the wrong thing though. Laptop memory doesn't look quite the same somehow :) mmm some of that 1G stuff looks interesting :D

But 133 seems only to go up to 512 each.

Memory prices are really weird though. The prices range from fairly small to £kkkk for what seems to be the same thing. Take the "kingstion value ram", pc2100 = £33, but what am I supposed to read into the label "value" ?

Sir Penguin
03-11-2004, 02:13:48
Basically, it means it runs a bit slower and you won't be able to overclock it much. :)

The thousands of dollars RAM is probably ECC and registered. It is extremely robust and does error checking and correction and stuff. It's a little slower than regular RAM, but it has a market in servers. It would be kind of silly to use it in a PC.

Laptop memory is indeed quite different. What you're looking for is SDRAM DIMMs. The SDR module will have 168 pins, and the DDR module will have 184 pins.

Another thing that I forgot about is that you might have to get RAM modules with the exact part number as the modules that are already in your computer. Some OEM computers don't like you to mix and match DIMM types.


03-11-2004, 08:34:36
Cheers. Was thinking latterly of getting 512Ms so if there proves to be a compatibility problem, best whip out the existing 256. (And flog it on ebay :))

Sir Penguin
03-11-2004, 08:47:47
I'm not sure if it's a matter of matching new modules to old, or matching new modules to the motherboard. Probably the former, but that's the sensible choice so it might not be true.


03-11-2004, 19:16:17
Just to be clear then, if there was a registered ram ecc PC133 going at a good price, I should avoid it because it's likely to cause problems ?

Sir Penguin
03-11-2004, 19:37:19


03-11-2004, 19:57:28
Right, I won't bid for this one then :( (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=6717954451&ssPageName=STRK:MEWA:IT)

Just as well I asked as I would have done otherwise. Possibly it's the "mistake" the seller says they made.

Mmmm may have guessed, it shot up a bit near the end anyway. Unsured I'd have topped the winning bid.