PC133 or PC100 memory?

[little_simon]

I was helping a friend upgrade her memory. She has a compaq computer with an AMD400MHz processor.

The current memory is a 64MB SDRAM PC100 and it works fine. But I installed a 256MB PC133 SDRAM thinking it would be backwords compatible. At least that's what everything I've read said.

The PC won't even power up the motherboard with the new memory installed. But it still works fine with the old 64MB PC100.

I installed it by itself and with both together, and it still wouldn't work. Do you think the 256 MB chip is fried? Or are they really not backwords compatible? Or am I missing something about the bus speeds? Any help would be appreciated...

Thanks.:D

[BipolarBill]

Most motherboards of that vintage can't accept anything bigger than 128MB. It's not the speed - it's the size.

[AllGamer]

Bill is right, it's just the stupid design of those older mobos

you can use many 128 meg 133 mhz RAMs but not 256 meg, cuz some mobo doesn't go that high

without a BIOS upgrade

so you can try that. :t

[little_simon]

Thanks a lot! I think you're right. It makes sense that the older motherboards won't take the bigger memory modules.

[RobUK]

Now come on guys don't be silly, a mobo that can handle a 400Mhz cpu is "vintage" and cannot take more than 128mb ram, i don't think so. I have had this prob with a friend and its a simple matter of the mobo doesn't like PC133 thats that! This was on an athlon system with an AMD750/751 chipset too and this can take more than a 256mb stick. ANY pc133 stick would render the machine useless, so just swap the pc133 stick for a pc100 stick and you should be fine. This mhyth about pc133 being backwards compatiable is nonsense it depends entirely on the mobo in question.

RobUK :t

[missiveusa]

It makes no sense to run PC 133 memory with PC 100 anyway, since the memory modules will both run at the lower speed. I'd install a 128 MB stick of PC 100.

[AllGamer]

what we meant was Sticks of RAMs
not total size
even vintage mobos as you call it they limit out at around 2 Gig of rams
yet some mobo only accepts sticks of 128 meg of RAM
and even with those 4 slot mobos
it'll be only something like 128 * 4
:t

[AllGamer]

Originally posted by missiveusa
It makes no sense to run PC 133 memory with PC 100 anyway, since the memory modules will both run at the lower speed. I'd install a 128 MB stick of PC 100.

is true that they run at lower bus speed to match

but now in days is easier and cheaper to get 133 RAM than finding 100 RAM, they are going extinct :D, and more pricey too

[BipolarBill]

Poop. The only SDRAM board I have ever had that wouldn't accept PC133 RAM was a ******* Intel i810 with a compromised memory translator hub. I sent it right back.

[grimfandango]

ahh just wanted to add somethin


my old p3 450 mhz could take 100/133mhz of any sdr ram up to 256 mb in each slot!

it had only two slots

total ram it could take was 512mb!


:t

[RobUK]

sorry bill but some mobos will not accept it, its a fact, also some ram is not backwards compatiable. This is all dependant on the quality of mobo and ram. You can't just dissmiss this. I have used a few mobos that have this problem. i have tried 64mb of pc100 in my old 166mmx setup (66mhz fsb) and this wouldn't boot either. This has an intel vx????? somthing chipset in it. So don't swear and me obnoxious, get all the facts. I am giving you this information from personnal experiance, not word of mouth!!

Allgamer i was talking about sticks of ram.

RobUK :mad:

[BipolarBill]

When did I swear? Poop? *******?

Main Entry: *******
Function: adjective
Date: 14th century
1 : ILLEGITIMATE
2 : of mixed or ill-conceived origin <known for coining ******* words>
3 : of abnormal shape or irregular size
4 : of a kind similar to but inferior to or less typical than some standard <******* measles>
5 : lacking genuineness or authority : FALSE

Put it this way - there are many more boards which cannot accept 256MB DIMMs than there are ones which cannot accept PC133 RAM. Not one of my six slot 1 Intel boards could accept double or single-sided 256MB DIMMs. My VIA MVP3 board couldn't either.

[AllGamer]

lets just put it this way

back then not many Individuals were able to afford 256 meg stick of RAM, cuz during that period remember the fires on those 2 RAM making plants in Asia?

that drove the prices sky high, and during that same period PCs was selling like hot potato.

so there wasn't enough people complaining or wanting too much RAM back then.

why do you think i went crazy now on my new computer, cuz the RAM prices are so dirt cheap :D

from 128 meg to 2 gig of RAM, for the same money a paid years ago just to get 128 meg of ram, and back then that was luxury to have anything more than 64 meg of RAM :p

that's quite a good change :)

but even back then i do know that brand names like Asus, Abit and GigaBytes did not have problem with the 256 meg Sticks, but they did warn that anything larger than 256 sticks might or will not work.

yet i still have some hard cover manuals from other mobos that they only specified 128 ram sticks, and not even a word about 256 meg sticks, and in fact a couple of those that had similar manuals did not work with 256 sticks.

so what Bill said is totally right :D

[tking]

Originally posted by missiveusa
It makes no sense to run PC 133 memory with PC 100 anyway, since the memory modules will both run at the lower speed.

I'd agree except I went out yesterday to update the memory in 4 Compaq P3-500 workstations and found that pc100 and pc133 are exactly the same price. Following overclocking logic I got the 133's figuring that they were engineered better and that they were backward compatible (I've never seen otherwise).

I threw the sticks in each of the compaqs and no problem. Sure they run at 100mhz, but it didn't cost me any extra so why not get the better built stuff?

Simon's friend's 400mhz amd Compaq sounds like it could be a cousin of our P3 500s. Never had a problem using 133 instead of 100, prefer it even for the above reasons.

T

[grimfandango]

Originally posted by BipolarBill

Put it this way - there are many more boards which cannot accept 256MB DIMMs than there are ones which cannot accept PC133 RAM. Not one of my six slot 1 Intel boards could accept double or single-sided 256MB DIMMs. My VIA MVP3 board couldn't either.


my ol one could take double or single sided 256mb...
Ithink all 440bx chipset can take 256mb ram!

am not sure!
:confused:

[AllGamer]

Agree, on the 133 to 100 thing

i've done that prenty of times

even with my old P2 board at 66, using 133 sticks LOL :D

it's only the size of the stick that matters as far as i can tell

say your mobo only read max stick of 256, then cuz now is cheap to get 512 stick you put them on, and that wont work

same case with 256 and old 128 only boards.

but bus speed problem is rare. :t

[BipolarBill]

Originally posted by grimfandango
am not sure!
:confused: I am sure - the entire Soyo 6BA+ series, the Abit BH-6, the Biostar M6TBA and the Soyo EHM would not accept 256MB sticks.

[missiveusa]

Simon: You can tell if it's a size problem by checking the maximum amount of memory that board can handle, info probably in manual. Then check number of slots. I suspect that COMPAQ has a 384 MB limit, with three DIMM slots. That means 128 MB per stick is the limit. Good luck sorting this out:x

[Buji]

Running a BH6 rev 1.2 here with a mix of 64(100), 64(133) and 256(133) from 3 separate makers and the only thing it didn't like was the order in the slots even though the manual said the order didn't matter.

[BipolarBill]

Hmmm. I don't recall which revision I had. Perhaps I'm mistaken about the Abit. I did find, however, that any Slot 1 board with 4 memory slots (Soyo 6BA+ is an example) wouldn't accept 256MB DIMMs. Granted, you don't really need that capability when you can drop four 128MB sticks in. They were certainly limited to 512MB total.

[omega31]

440BX boards (good ones) can use 1 gb of memory. I have a P2B-F, and though I'm not using more than 512 mb now, I could do it and have done it.

[Jsnyderj]

YOu can send me the 256 meg pc133 and i ll send you 2 128 pc100 sticks. You still get 256 out of it ..

And just for kickers .. how much ram does the Mobo support anyhow .. should say on the site for the mobo...

if it supports 768meg ram then it will support the 256.. but your computer may not support that form of ram .. the rom chip on the memory you have may not work with your mobo .. I'd bring it into a compusa or a computer store and have them check the stick of ram to make sure you didnt burn it out .. if not .. I ll be happy to trade .. I have lots of ram around .. I'll guarentee it to work with your system ..

Get back

Jack :t

[AllGamer]

Ok people i think little_simon, got a very good idea already.

it's time to move on to another thead and argue about other things

:D :t

[grimfandango]

Originally posted by omega31
440BX boards (good ones) can use 1 gb of memory. I have a P2B-F, and though I'm not using more than 512 mb now, I could do it and have done it.

yea!
:)

it depends on whos makin the board too!!

:)

[Peter M]

Keep the facts straight folks ... the older mainboards can't accept the really large DIMMs because the chipsets can't.

Note the limit is a size limit, namely in the rows-by-columns size per SDRAM _chip_.

1st generation SDRAM chipsets (Intel 430VX, VIA VP-1, SiS 5571) could only do 16 MBits per chip, 16 MBytes per DIMM side, 32 MBytes per DIMM.

The next round (Intel 440 series, VIA VPX, VP3, MVP3, Apollo Pro, Pro+, SiS 5581 to 5600, ALi Aladdin IV, IV, Pro II) do better, with a maximum of 128 MBits per chip, 128 MBytes per DIMM side, 256 MBytes per DIMM.

Current chipsets can do up to 512 MBit per chip for 1-GByte DIMMs.

Note that with the still quite popular 2nd generation chipsets, you'll notice that there are THREE different flavors of 256-MByte DIMMs:

Truly double-sided (read: 2-bank) ones made from 16 pcs "16x8" chips. These are compatible with all the chipsets I listed above.
Then there are those that look the same but are quite different - these use 16 pcs of "32x4" chips to form one single bank of 256 MBytes - which logically makes them single-sided. These do not work on the older chipsets, neither do they on any Intel chipset no matter how new.
Finally the obviously single-sided 8-chip DIMMs also don't work on the older chipsets.

Boards that take the "16x8" flavor SDRAM reach back to 1997, provided their makers updated BIOSes long enough to include detection for them. Manuals are often outdated regarding this, because they usually list what was available when the manual got printed (which happens before the board is hitting the shelves).

BipolarBill, dunno what boards you had there, but actually there is not one Pentium-II chipset that can't do 256-MByte DIMMs, provided you got the right flavor ...

And finally, to burst AllGamer's "major brand" bubble, the two oldest boards I've ever run 256-MByte DIMMs in are both from PC-Chips, M537DMA33 and M560, both from mid-1997.

regards, Peter

[RobUK]

Sorry bill still stand by my opinions, as i have had experiance with this. BTW ******* is not a nice word to say, in england aw. If this were my forum it would have been blanked out! Keep this in mind! Keep the standards of the forum please! Some ppl get offended by this.

I also agree btw that 90% of the time pc133 memory is backwards compatiable, but there is still the other 10%! remeber what works for one person doesn't alsways work for another!

RobUK

[omega31]

Thanks, Peter. I was gonna mention what you did, but I couldn't find a precise and succinct way telling it. I was ready to submit, but it looked really messy and I would have just confused everybody, including myself.

:t

[BipolarBill]

Originally posted by RobUK
BTW ******* is not a nice word to say, in england aw. If this were my forum it would have been blanked out! Keep this in mind! Keep the standards of the forum please! Some ppl get offended by this.Rob, please don't push me on the B word. I am the moderator, not you. If you would like to suggest that this word be added to the swear list, you may do that. The way I see it, that definition is from the English dictionary. It's no more dirty than the word feces. It is more legitimate than many people I know. ;)