Scheduled Maintenance: We are aware of an issue with Google, AOL, and Yahoo services as email providers which are blocking new registrations. We are trying to fix the issue and we have several internal and external support tickets in process to resolve the issue. Please see: viewtopic.php?t=158230

 

 

 

Compatible RAM faster than backward compatible RAM?

Off-Topic discussions about science, technology, and non Debian specific topics.
Post Reply
Message
Author
tien07
Posts: 13
Joined: 2007-04-10 08:17

Compatible RAM faster than backward compatible RAM?

#1 Post by tien07 »

I have 400MHz RAM, but my motherboard only supports up to 333MHz. So my motherboard would automatically underclocks it to 333MHz.

I was told that a 333MHz RAM runs faster and better than an underclocked (to 333MHz) 400MHz RAM. Is this true?

I always thought that it would be the same.

User avatar
chrismortimore
Posts: 849
Joined: 2007-04-24 06:34
Location: Edinburgh, UK

#2 Post by chrismortimore »

The difference is probably negligible.
Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 5x320GB WD 7200rpm Caviar RE2 (RAID5), Nvidia 6600GT 256MB
Laptop: Intel Pentium M 1.5GHz, 512MB PC2700, 60GB 5400rpm IBM TravelStar, Nvidia 5200Go 64MB

User avatar
sinical
Posts: 1012
Joined: 2007-03-25 11:52

#3 Post by sinical »

I doubt even a benchmark could tell the diffrence
Every cloud has a silver lining, except for the mushroom shaped ones, which have a lining of Strontium 90.
---------------------------------------------
umop apisdn

User avatar
swirling_vortex
Posts: 631
Joined: 2007-02-16 20:30
Location: Pennsylvania

#4 Post by swirling_vortex »

RAM moves data so fast, the clock speeds don't matter too much unless you need very high performance out of your system. Even then, Linux manages RAM much better than Windows anyway, so I don't think you have anything to worry about.

User avatar
diego1116
Posts: 352
Joined: 2007-03-28 17:49
Location: Santa Maria, RS, Brazil

#5 Post by diego1116 »

Probably you was told about sync/async modes and your case seems slightly different. Just found something at http://forums.pcper.com/showthread.php?t=320351:
Dealing with Memory Speeds: What is sync / async?

(NOTE: ..Does NOT include the Athlon64/FX. They are alot different when it comes to this ...will be updated shortly).

When the memory frequency runs at the same speed as the FSB, it is said to be running in synchronous operation. When memory and FSB are clocked differently (lower or higher than), it is known to be in asynchronous mode. On both AMD and Intel platforms, the most performance benefits are seen when the FSB frequency of the processor is running synchronously with that memory – Although Intel based systems have a slight exception, this is completely true of all AMD-supporting chipsets. Only Intel chipsets have implemented async modes that have any merit. The async modes in SiS P4 chipsets also work correctly. When looking at the AMD-supporting chipsets async modes are to be avoided like a plague. AMD-supporting chipsets offer less flexibility in this regard due to poorly implemented async modes. Even if it means running our memory clock speed well below the maximum feasible for a given memory, an Athlon XP system will ALWAYS exhibit best performance running the memory in sync with the FSB. Therefore, a 166FSB Athlon XP would run synchronously with DDR333/PC2700 (2*166) and give better performance than running with DDR400/PC3200, despite its numbers being bigger. This does not mean to say that PC3200 isn’t a good idea for 166FSB Athlon XPs. Buying slightly higher-rated memory than needed is a good idea if your intent is to overclock and it also allows you some future upgrade room.

To achieve synchronous operation, there is usually a Memory Frequency or DRAM ratio setting in the bios of your system that will allow you to manipulate the memory speed to a either a percentage of the FSB (i.e. 100%) or a fraction (or ratio) i.e. N/N where N is any integer available to you. If you want to run memory at non 1:1 ratio speeds, motherboards use dividers that create a ratio of [CPU FSB]:[memory frequency] or through the use of percentages of the FSB. However, intrinsically, it is possible to see the problem with this and why synchronous operation is preferable on all PC platforms. If for there is divider, then there is going to be a gap between the time that data is available for the memory, and when the memory is available to accept the data (or vica versa). There will also be a mismatch between the amount of data the CPU can send to the memory and how much the memory can accept from the CPU. This will cause slowdowns as you will be limited by the slowest component.

tien07
Posts: 13
Joined: 2007-04-10 08:17

#6 Post by tien07 »

Yes, the sync/async is what I was talking about. But could not have explained it better, because I did not know very much about it or the proper term for it.

I was hoping to get some opinions from experienced users.

So if I have a CPU FSB at 133MHz (266) and my RAM is at 266MHz, would it run more efficient than if it would with a 333MHz or a 400MHz RAM?

User avatar
llivv
Posts: 5340
Joined: 2007-02-14 18:10
Location: cold storage

#7 Post by llivv »

'
Last edited by llivv on 2019-02-15 17:12, edited 1 time in total.
In memory of Ian Ashley Murdock (1973 - 2015) founder of the Debian project.

User avatar
DeanLinkous
Posts: 1570
Joined: 2006-06-04 15:28

#8 Post by DeanLinkous »

lots of opinions in this thread.... :P
Now let me offer mine :lol:
Aye, fight and you may fail, sellout, and you may live, a while. And dying in your MScash beds, you'll be willin' to trade ALL the cash, to come back here and tell our enemies that they may FUD our customers, but they'll never take...OUR FREEDOM!

Post Reply