512MB PC133 OR 512MB PC133 & 64MB PC100 - Which is Faster?

[LABachlr]

I am building a system for a friend, and I have a 512mb PC133 chip in there now. His old system had a 64mb PC100 chip in it. My question is, will it help the system to install the additional RAM chip, or will it slow it down seeing that it is only a pc100 chip? Will it make the 512 chip run at pc100 as well, or will it only run at 100MHz itself.

By the way, for some reason, I was not able to jumper the mobo, MSI MS-6378, to 133MHz FSB...only to 100MHz FSB. The cpu is a AMD Athlon (supposedly a Thunderbird; how do I check?) 1.1GHz. Does that only have a FSB of 100MHz? Also, I assume that the FSB and the speed of the RAM are independent of each other, right?

[$1500-P4 gamer]

If its a tbird then they only have a 100fsb anyhow. Second running it at 100/133 can be instable Ive been there. Keep it synchronis I.E. 100/100. Yes adding more will speed it up too. And yes the pc133 with a stick of pc100 will lower itself to 100mhz aswell so as to operate within spec. Its backward compat. Go for it man.

[LABachlr]

Originally posted by $1500-P4 gamer
If its a tbird then they only have a 100fsb anyhow. Second running it at 100/133 can be instable Ive been there. Keep it synchronis I.E. 100/100. Yes adding more will speed it up too. And yes the pc133 with a stick of pc100 will lower itself to 100mhz aswell so as to operate within spec. Its backward compat. Go for it man.

So you're saying that 576MB of PC100 RAM is faster than 512MB of PC133?

[Bovon]

Originally posted by LABachlr


So you're saying that 576MB of PC100 RAM is faster than 512MB of PC133?

Somehow I believe you may have the wrong concept on speed where ram is concerned. Ram runs at the same bus speed the processor runs at, unless the motherboard has provisions to do that another way... I think some moterboards will run the ram at one speed and the processor at another, but I am not sure of this.

PC 100 will work at 100 mhz. Most times, depending on the CAS value and quality of the ram chips..it will run at bus speeds above 100. I recently tested some PC 100- CAS2 at 150 mhz fsb...a CAS3 module would have failed before 150 mhz probably.

PC 133 will run at 133 mhz bus..it will usually run at higher speeds as well, just like the PC 100.

Here is the main difference. You have a stick of PC 100 that will run up to (say) 140 mhz. You also have a stick of PC 133 that will run up to 160 mhz...you have both of these modules in the same machine, and you want to overclock it. The best you can possibly do is 140 mhz...limited by the PC 100 module. The ram modules are speed limited, but have little to do with how well (or fast) your system runs, until you hit the speed ceiling for any one piece of ram in the system.

A Duron or Tbird will run at 133 mhs fsb if it is unlocked. Most were shipped from the factory locked...look at the L1 bridges out on the ceramic base (itsy bitsy gold colored traces about 1/32 of an inch long...there are four of these.) If they are laser cut, then the processor is locked and will only run at 100 mhz fsb. The L1 (cut traces) can be rejoined with a conductive ink, and the cpu will now run at 133 mhz fsb.

Depending on the OS (Windows version) you may not be able to install over 512 mb of ram...this was true with the Win98 series...and even some of the more recent Windows versions appear to get sluggish with too much ram is installed. For a non gaming machine...ie...a home surfing, light gaming machine, 512 mb is more than enough.

[Bigjakkstaffa]

Id use the 512mb of PC133 as the 1.1ghz tbirds are very good overclockers on the FSB and the extra room will help a lot, especially while running agressive RAM timings.

As for tbirds only runnign at 100FSb - wrong. From the 1ghz model there have been 133fsb variants.

--Jakk

[germanjulian]

nevermind that you only gain about 4% performence increase between 100Fsb and 133FSb ram speed is not the most important thing

[Bigjakkstaffa]

But when you take the 4% from the extra 33FSb add it to 4 way interleave, turbo mem timings, CAS 2 your talkign quite a gain

--Jakk

[dave-harper]

um - 1100 mhz / 133.333 mhz = 8 1/4 ( not )
i find it weird enough to run at say 8 1/2
yours is 1100/100 = 11x multiple

the main thing is ( not 12% ! more mem ) BUT are you using the old windows - what version is it - the older ones went stupid with more than 512 ram and worked WORSE

the manual is here but it's the stupid ( .exe ) self extract and they are for 3 different versions !!!!!
http://www.msi.com.tw/program/suppor...2&NAME=MS-6378

if you leave it all set to auto it will probably do fine and have the cpu at it's proper 100 and the 512 at it's 133

there is discussion about synchronous between the cpu and mem or not but more with 166 and 200 mem and the fancy cas2 settings
yours is enough different ( 33%) between 100 cpu and 133 mem i would let it go auto
even if you fixed the windows prob or had none i think the extra 12% mem wouldn't be worth slowing the ram to 2/3 speed which adding the slower stick WOULD do