Will PC133 downclock too PC100?

[Tab]

Just a simple question. I have a 850Mhz Celly and I was thinking of buying some PC133. PC100 wasnt avilable at Best Buy. The tech said it wouldnt, but I really honestly dont trust them.

 

[spanky]

i've had pc133 ram in a 100mhz fsb system before.

 

[BlueWeasel]

Correct me if I am wrong, but I think PC133 will lower its clock to run at lower speeds (PC100, PC66, etc.)

 

[bozo1]

PC133 will run at 100mhz just fine.

However, if you buy a 256Meg stick, make sure that it has chips on both sides as your motherboard probably does not support high-density memory.

 

[PCMarine]

Originally posted by: bozo1
PC133 will run at 100mhz just fine.

However, if you buy a 256Meg stick, make sure that it has chips on both sides as your motherboard probably does not support high-density memory.

Exactly. Especially watch out for the nasty generic HIGH DENSITY ram.

 

[John]

The tech said it wouldnt, but I really honestly dont trust them.

That's one reason chain store technicians get a bad wrap. Most of them don't know their head from their @$$.

 

[njeske]

Or they just lie to get you to pay more.

 

[Lord Evermore]

Lots of PC100 modules that won't get sold otherwise.

 

[ssanches]

PC133 is backward compatible and can definitely run at 100 and 66 Mhz speeds. In fact I'd suggest that you go for PC133 over PC100 for your setup. The reason behind this is simple: PC133 CL3 can always run as PC100 CL2. IIRC, that's part of the PC-133 spec for 7.5ns chips.

 

[Adul]

yes it will work finr at any speed from pc133 on down

 

[Tab]

I thought so, right now I 'think' I have a PC100 stick in my 850Mhz Celeron. Will it work if I get a PC133 Stick and I still have a PC100? Or will I need to get a single PC133 and downclock that and use that?

 

[CrazyHelloDeli]

Originally posted by: Tabb
I thought so, right now I 'think' I have a PC100 stick in my 850Mhz Celeron. Will it work if I get a PC133 Stick and I still have a PC100? Or will I need to get a single PC133 and downclock that and use that?

Yes, it "should" work. Ive run into plenty of systems that want theyre speed memory and nothing else, high density or not. I always recommend using whats qualified for the board when talking SDRAM. Just personal experiance.

 

[Tab]

I was talking to a computer expert and he said that the newer Ram is going agaisnt the JEDEC specs for a auto-detect SPD, meaning it will not downclock anymore. Maybe the computer tech was right, to a point.

 

[amdskip]

Originally posted by: Tabb
I was talking to a computer expert and he said that the newer Ram is going agaisnt the JEDEC specs for a auto-detect SPD, meaning it will not downclock anymore. Maybe the computer tech was right, to a point.

believe me, he's not an expert

 

[psianime]

It should downclock without any problems.

-psianime

 

[kugai]

yes, pc 133 is fully backward compatiable

 

[0roo0roo]

some m/b will run asynchronous clock speeds. 133mhz for sdram 100 for cpu. thats what i did when i had a celly 850.

then again only some m/b will do it

 

[Lord Evermore]

Boards that won't accept anything but PC100 are a problem because they don't allow you to specify the memory speed in the CMOS setup, and the BIOS is programmed to only run PC100 memory. When the BIOS reads the SPD chip on PC133 memory, it sees that it is not PC100 and will fail to work, even though the memory is actually better than the requirements. This is mainly an issue with server boards, primarily OEM systems where they want you to only buy their brand of memory to upgrade or replace, so they try to make the range of available parts as narrow and rare as possible.

Any normal consumer/enthusiast board will allow you to specify at a minimum whether to run the memory at 66MHz, 100MHz, or 133MHz; better boards also provide options to change other timings. Setting the "by SPD" option for memory speed won't work for the same reason the server board won't use it, but manual settings will work fine.

The memory itself can ALWAYS be downclocked manually. Whether the motherboard allows you to manually set the speed is another issue.

 

[mrman3k]

You can downclock memory in most cases, unless of course the motherboard forces faster memory speeds.

 

[FrustratedUser]

Ohh yes.

 

[Boobers]

This last weekend I tried to install a Kingston 256Mb High-Density SDRAM in a Compaq Presario desktop. The motherboard had an Intel 810E chipset, which required 100Mhz RAM. I had always thought that PC133 would work in a PC100 board, but it would not boot. The Compaq had no BIOS settings for RAM speed, so I think it read the speed from the RAM and since it wasn't PC100, it refused to boot.

So, for those of you who say "sure, PC133 will always run in a PC100 board", think again. Now, maybe the problem is that new SDRAM's are high density (only have chips on one side of the circuit board). I have some older Kingston SDRAM that has chips on both sides, and I will try them soon to see if they work. But I suspect it will read the PC133 speed and still refuse to boot.

Some motherboards are designed (rigged) by the manufacturers to accept ONLY PC100, and will NEVER run PC133. YMMV...

 

[Lord Evermore]

Nobody said PC133 will work in any PC100 board. We just said PC133 can be run at PC100 speeds. I also already pointed out that some systems won't run PC133 memory at PC100 due to having been programmed to read the SPD and only work if it's programmed as PC100. The downclocking will of course only work if the motherboard allows you to specify the speed to run the memory at.

It should also be pointed out, I don't think anyone did, that Crucial.com sells very good, CL2 PC133 memory for less than half the price of the lowest priced memory at Best Buy (which is probably CL3), and Crucial ships free and always gets stuff to me within one day. PC100 is slightly more expensive, but still only 3/5th the price of Best Buy's PC133.

 

[Boobers]

I just bought Kingston 265Mb PC133 SDRAM @ Best Buy for $13.00 (after rebate). Let's see Crucial top that. Right now it's running CAS2 @ 140Mhz...

 

[Lord Evermore]

Rebates are offered because companies know that 75% of people aren't going to redeem them. Many times they also have time limits that you wouldn't expect.

As for beating it, Crucial PC133 rated for CL2 could probably beat 140MHz. Not worth the extra cost, I'd go for the Kingston, yes, but only if I could get the rebate.

 

[arcenite]

PC133 SDRam will work at speeds of 133Mhz and lower.

Bill