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  • Shade[ST]
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RAM Bus Speed
Hello,

I just bought myself two sticks of 512mb ram (DDR400) which I added to my system.  It already had 512 mb of DDR266, and I was wondering whether I should remove the old ram from my system -- would that make it faster or slower?  Has anyone had experience with different ram speeds and how much it affects system performance?  I've looked for benchmarks on google, but found nothing.

Thanks,
Tristan.

  • pest
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RAM Bus Speed
Reply #1
depends on the motherboard-chipset. does it support interleaving? test for yourself 

  • Teqnilogik
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RAM Bus Speed
Reply #2
Well, first does your motherboard support DDR400 memory?  If it doesn't it would be operating at the fastest speed your motherboard supports.

If it does then you can benchmark with SiSoftware's Sandra product.  I believe it has a memory benchmark in the free product that you can run.

  • Axon
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RAM Bus Speed
Reply #3
Real-world improvements due to improved RAM timings are usually fairly marginal. You can see large improvements on artificial benchmarks, 1-3% improvements for certain applications and games, and 0.01% for everything else.

  • Shade[ST]
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RAM Bus Speed
Reply #4
Real-world improvements due to improved RAM timings are usually fairly marginal. You can see large improvements on artificial benchmarks, 1-3% improvements for certain applications and games, and 0.01% for everything else.
Thanks.  I guess I'll just leave the extra 512 mb in, then?  Vista'll like it

  • saratoga
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RAM Bus Speed
Reply #5
Real-world improvements due to improved RAM timings are usually fairly marginal. You can see large improvements on artificial benchmarks, 1-3% improvements for certain applications and games, and 0.01% for everything else.


Depends on system.

DDR266 vs. DDR400 gives a 13% difference in Q3 for the A64: 

http://www.digital-daily.com/cpu/amd-athlo...ter/index04.htm

In synthetic benchmarks, you'll likely see a 50% difference.  Though obviously you'll need a system that can match the RAM you buy to take advantage of it.

RAM Bus Speed
Reply #6
System will only run as fast as the slowest ram.
"You can fight without ever winning, but never win without a fight."  Neil Peart  'Resist'

  • music_man_mpc
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RAM Bus Speed
Reply #7
Real-world improvements due to improved RAM timings are usually fairly marginal. You can see large improvements on artificial benchmarks, 1-3% improvements for certain applications and games, and 0.01% for everything else.

First of all memory timings are different then memory clock speed, which happens to be what is being discussed here.

Second of all a 3% improvement for one minor tweak is quite significant, tweaks add up and I, for one, wouldn't just give away 1-3% system performance when it is just there for the taking.  Any decent DDR can run 2-2-2-5 at stock speed.

Memory clock speed makes little to no difference when it exceeds the FSB speed.  I had a board that used to have a 5/4 memory clock to FSB ratio, settings like that do nothing or near nothing.  However if your RAM is running BELOW your FSB speed increasing its clock will likely have a prfound impact.  Which makes logical sense as the system is only as fast as its slowest bottleneck.

In conclusion, if Shade's MOBO and CPU can run at a faster FSB then 266 (and if clocks it this high) he should definately dump the old ram, if not he should keep it.
gentoo ~amd64 + layman | ncmpcpp/mpd | wavpack + vorbis + lame

  • Landus
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RAM Bus Speed
Reply #8
Just to translate some of that for those that are completely lost.

FSB stands for Front Side Bus. It's connects everything. CPU, RAM, PCI/AGI slots, chipset.

I use this example to dumb it down. Think of the FSB as a highway. It has a set speed limit. How fast everything can travel is dependant on how fast the speed limit of the FSB is.

  • Shade[ST]
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RAM Bus Speed
Reply #9
Just to translate some of that for those that are completely lost.

FSB stands for Front Side Bus. It's connects everything. CPU, RAM, PCI/AGI slots, chipset.

I use this example to dumb it down. Think of the FSB as a highway. It has a set speed limit. How fast everything can travel is dependant on how fast the speed limit of the FSB is.

Yeah, I understand the tech stuff, and my processor is an Athlon 64 3000+, so I presume the FSB will run at 400Mhz.  I'm not so sure I should remove the 512 megs of 266Mhz ram, though.  Are you guys sure?

  • rutra80
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RAM Bus Speed
Reply #10
That's weird, how come that you had 266MHz RAM with Athlon64? They run with 400MHz FSB, CPU speed (in MHz) = multiplier * FSB, so assuming that you have Socket754 Athlon64 which for 3000+ is clocked at 2000MHz, its multiplier is 5 (2000 / 400MHz = 5). Now there are four possibilities:
1. Your CPU was underclocked all the time (266MHz RAM * 5 = 1330MHz).
2. Your 266MHz RAM was running at 400MHz so it was heavily overclocked all the time.
3. You manually set your system to run assymetrically (different clocking for FSB & RAM) which is suboptimal.
4. You manually increased your multiplier to 7.5 (266MHz RAM * 7.5 = 2000MHz) - I'm not even sure if it is possible to change multipliers in Athlons64...
You better check which case it is because none of them are good.
  • Last Edit: 17 June, 2006, 12:26:27 AM by rutra80

  • Shade[ST]
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RAM Bus Speed
Reply #11
I upgraded my CPU from an Athlon XP 2400+ which had 266Mhz ram.

Right now, my 3000+ is at 1.89 Ghz.

  • rutra80
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Reply #12
So it's Socket939 and its multiplier is 4.5. Since your CPU is running at full speed, #1 is not the case. You should check if it's case 2, 3, or 4.
Anyway, if you add that 400MHz RAM, you'll have more memory, but there's more risk that things will get unstable - since there will be more than one module, your system will probably try to switch to dual-channel mode, which sometimes fails when there are more than two modules (of different brands), not to mention different clocking and timings.
If you get rid of the 266MHz RAM, you'll have less memory, but there won't be instability risk and it will be faster (non-overclocked 400MHz in dual-channel mode).
  • Last Edit: 17 June, 2006, 03:06:25 PM by rutra80

  • sony666
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RAM Bus Speed
Reply #13
memory makes no huge difference, but that 133 MHz DDR stick doesn't really fit an AMD 64
I would not use that

  • Shade[ST]
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RAM Bus Speed
Reply #14
My BIOS says my FSB is at 266 Mhz.  Memtest says my RAM is single-channel, 266 Mhz.  The question is, far from sub-optimality, how much "better" can it get?  Will I get 50% increased performance?  Let's say I usually do photoshop work, what difference will it make?

RAM Bus Speed
Reply #15
You'll get a lot more out of having more ram than you'll ever get out of having faster ram. On a direct comparison you might get 10-20% more performance in apps that chew on a ton of memory every operation, like photoshop with zillions of layers, otherwise you're looking at a barely noticable improvement.

If the nature of your photoshop work hardly stresses memory (like 100M+ per operation) or uses cpu-heavy operations then faster memory won't help.

Of course you can always take the old stick out, and put it back in if it doesn't make a difference.

  • rutra80
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Reply #16
Quote
' date='Jun 17 2006, 23:16' post='403970']
My BIOS says my FSB is at 266 Mhz.  Memtest says my RAM is single-channel, 266 Mhz.

That's odd, CPU running at full speed while RAM & FSB is at 266MHz? Could you please check these things again with CPU-Z?
Quote
The question is, far from sub-optimality, how much "better" can it get?  Will I get 50% increased performance?  Let's say I usually do photoshop work, what difference will it make?

I doubt you would get 50% increased performance. Do some benchmarks on your current configuration, replace 266MHz RAM with 400MHz one and compare, you will see.
  • Last Edit: 17 June, 2006, 09:31:23 PM by rutra80