Backward Compatible

Little help needed. I thought backward compatible meant that for example a PC2100 memory stick would work in a system that was rated at a speed of say PC2700 or PC3200, but at the lower speed or is it the reverse?

The reason I am asking this question is because I install a PC2100 memory stick in what appears to be a PC3200 memory system, which I didn't find out until I removed the original memory stick. All the information on HP's website and memory websites said my system used a PC2100 Stick. Also, does a continuous beeping occur when you have an incompatibility issue?

 

Pete, I can forget about going to www.crucial.com. They and HP got me into this mess to begin with. Like a fool I believe Crucial and HP when they told me that I needed DDR PC2100 for my HP Pavilion A610y system. I guess everything was based on HP's support website. As best as I can tell I have a mismatch of memory speed which is causing my problem. I plan to pull the original memory and recheck it to see what is really there. I think it is DDR PC3200, which is great, if I had known this in the beginning, but I made the mistake of relying on other sources. Oh well the grandson will be happy with is new memory for Christmas. His PC actually uses DDR PC2100. I know this because I put it in when I purchased it.

 

bmartin

Bassackwards is the word. Sorry to hear of your misfortunes but it appears that you will be keeping it "in the family" so to speak - that's not all bad. Generally speaking, Crucial is pretty reliable but I too have some reservations in this regard - have seen a couple of systems where it ran like garbage and I tend to stay away from it except for generic replacement.

If you are looking for good PC3200 non-ECC DDR memory at a most affordable price, go to NewEgg and buy Samsung 256MB modules at roughly $44-48 per stick. This will run extremely well on most any board made and you won't touch it with anything you can buy at retail. Although I use a lot of OCZ and Corsair specialty memory on high end boards, I have never been disappointed in Samsung and now use it almost exclusively in all but the most demanding of situations. You'll find it here.

 

Ok. I pulled my memory and it is a PC3200, 512MB, 400Mhz, CL3 type. I went to newegg as suggested and found a real good deal for a similar memory stick, except in the specs the CL shows as 2.5 and on the install stick it is CL3. Will this be a problem if I purchase this memory stick and install it in my 2nd slot?

 

Hopefully, you will wind up being a happy camper and there's nothing wrong with your approach if thats what you want to do, but its not my recommendation or my suggestion. There's an old adage for your behavior, its called "Let the buyer beware ". Good Luck.

 

Understood. I just wasn't sure about the CL rating difference that I found on the installed card and the one I found at newegg. All other specs are the same.

 

For everybody's info: Beep Codes http://www.computerhope.com/beep.htm#04

Regards - Charles

 

OK, now I am really confused, but that's nothing new. Here is my situation.
I was in my BIOS settings looking for my FBS and Processor temperature info and I saw the Memory Type listed as 512MB/PC2100. When I pulled my memory board the other day from the slot it showed 512MB, PC3200, 400Mhz. Now which do I believe. I can tell you this for sure when I installed a 512MB/PC2100, 266Mhz card I got one short beep and the computer would not start up. So do I believe what is on the label on the memory card in the PC or the BIOS information. No wonder My HP specs on my system is ***** up. Do I assume that someone put the info in my BOIS settings and It is wrong? Is there a program that I can run that will tell me just what is in my system?

Also, while I am on the BIOS is there any reason why I can't find my FBS for my system listed anywhere. Is there a secret about the setting that I am not aware of when I am looking through the menu and setting for my system.

 

Hello bmartin,

Is there a program that I can run that will tell me just what is in my system?

Lets see what Everest says: http://www.lavalys.com/index.php?page=product&view=1

Regards - Charles

 

Lets see what Everest says:

Give lots of info. Good tool I will keep it install for future info about my computer. However, did not tell me the memory type PC2100 or PC3200.

I think based on what I know now I should believe the label on the install card.

 

Go to the HP web site, punch in your ticket #, serial # or order # (one of those will do the trick) and you can reference the specs on your machine as it was originally configured. My suspicion is that you were running PC3200 at 266MHZ memory speed (PC2100) - thats not necessarily uncommon. Understanding that not all memory is created equal, the PC2100 you tried to install was more than likely some "generic budget buy" memory that choked your computer. Backing off your memory timings probably will let you run with that stuff but ......

So whats right - they both are more than likely correct. Are we having fun yet? Be careful mucking around in the BIOS - you can render yourself unbootable vey quickly.

 

Rockster2U, I get your point, but I find it hard to believe the the label on the card install in my system says PC3200, 512Mb, 400Mhz, if the card is a PC3200, 266Mhz. I will check HP website, but they were the ones that got me into this mess in the beginning by showing and telling me that I had a PC2100, 512MB shipped in the system.

 

No, no, no ..... there's a misunderstanding here. You probably do have PC3200 which is rated to run at 400mhz; however, it is probably only set to run at 266mhz, the equivalent speed of PC2100 memory. This is called, just like your thread, backwards compatability. One of the determinants and quite possibly the limiting factor in your case is the bus speed of the mainboard chipset. If your bus speed is only 266MHZ, then any faster memory you put in there is going to (default to) run at 266MHZ or the equivalent of PC2100, unless you have a motherboard that will permit you to increase the memory speed independent of your system BUS. More advanced motherboards have incremental settings so one can adjust things like this - I doubt (but can't say for sure) that your motherboard is going to be in that category.

To compound the agony, there are other common memory settings that go way beyond the relatively simplistic speed and latency references you questioned earlier. (2.5 vs 3.0 CAS or column address strobe) Most good memory will carry a basic recommended setting that looks like this ( 2-3-2-6-1T ), which translates to:
2 - CAS
3 - TRCD (RAS to CAS delay)
2 - TRP (RAS Precharge)
6 - TRAS (Active to Precharge)
1T - Command Rate

Not trying to be your professor here and certainly am no preacher, just another way of saying - not all memory is created equal. We've just touched the surface re: memory settings but don't let it get you too frustrated. This can get real complex the deeper you go into fine tuning - not to worry, HP didn't afford you those options so you can breathe a sigh of relief. If you bought that stick of 512MB PC3200 that you referenced a couple of days ago, it will probably work just fine.



edit afterthought: Everest will tell you what each module is - check again.

 

Ok, dummy here is on the same page. Thanks

 

Ok. Dummy here is finally on the same page. However, I do have one other question for you. You mentioned generic stick as maybe being my problem with the PC2100 stick that did work in my system. The card is a Samsung 512MB PC2100 , ECC /184-pin/CL2.5. I don't Samsung is generic. Anyway, I am now finding that it will not work in my Grandson's system, which is a 266Mhz speed. I am starting to believe the memory card may be bad since I can't get it to fire up in any system I put it in. Maybe that's is the reason that I got it at such a good price????????

 

The problem is that one can't mixed unbuffered (non-ECC) memory with ECC (error correcting code) memory. The stick is more than likely good. Most home user PC's require unbuffered memory.

Don't feel like a dummy - you're not the first one to walk down this path and you won't be the last. Think about what you now know vs where you were a week ago. Not exactly good cocktail party conversation, but it will come in handy at some point in time.