DDR vs SDRAM

[KiloZ]

Hello all,
I've heard that DDR or RDRAM is superior to SDRAM, but I'm not sure why.
I ask because I'm in the process of upgrading my system's RAM; currently it's got 512 megs of Mushkin CAS2 (PC-133) - which I thought was pretty fast. Also, since I still have an empty DIMM, would it be okay to simply install some DDR which means I would be mixing SDRAM and DDRAM. Can that cause problems?
And lastly, if money was no object, what type of RAM would you install?

Thank you in advance!

All great accomplishments were once considered impossible.

 

[cdogg]

If you just search this site, you'll find a ton of threads that have addressed this in the past.

However, the quick answer is that MOST motherboards don't give you the option to run both types of RAM (each is physically a different size requiring a different slot).

Just upgrading RAM isn't going to provide that much of an overall performance boost, especially if you're already at 512MB. Unless you have a newer OS like Windows 2000 or XP, the extra RAM will probably do very little good. Plus, older motherboards might have a small limit (many are either 512MB or 1GB). So be sure to check your specs.


~cdogg
[tab]"All paid jobs absorb and degrade the mind";
[tab][tab]- Aristotle
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[micker377]

The advantages of DDR (if your motherboard allows it), is the cycles of usable ram. Basically 133 SDRam works at 133, DDR uses both the "up" ramp AND the "down" ramp of the memory cycle. DDR = Double Data Rate. You will effectivly running at 266. AMD CPU's only run at full speed with DDR. You probably won't see any real gain unless you are running a memory intensive program like Auto-Cad.

 

[cdogg]

AMD CPU's only run at full speed with DDR

Just want to clarify that this isn't necessarily true for ALL AMD CPU's. As a matter of fact, it only applies to models that use a 333MHz FSB or higher. For all others that use a 266MHz FSB or slower, there are motherboards which support PC100 and PC133. Both have the ability to run in synch with a 100MHz or 133MHz system bus. Remember, the CPU's frontside bus is just doubling it.

I wouldn't want to run SDRAM with an Athlon, but it is possible on older versions!


~cdogg
[tab]"All paid jobs absorb and degrade the mind";
[tab][tab]- Aristotle
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[KiloZ]

Oh...ok. That is very good to know since I am running a AMD Duron CPU (an 650 overclocked up to 900MHz). My FSB is also overclocked to 200 MHz (from 100) but I did not know that about my RAM. Thank you ALL very much for the most helpful information!
I will verify that my motherboard is DDR-capable. It's an ABIT KT7 with the VIA VT8363/KT133 chipset.



All great accomplishments were once considered impossible.

 

[satrow]

Your FSB is not overclocked - it is internally doubled from 100FSB - that is standard. I have a Duron 700 that has been running perfectly for over 3 years on a FSB of 115(230) with PC133 SDRAM; just make sure the CPU has excellent cooling and the Temperature alarm in the Bios is set to shut down in the event of overheating or CPU failure.

Andy.

 

[cdogg]

Kiloz,
Yeah, don't let that confuse you. The frontside bus only pertains to the CPU. For AMD CPU's (Athlons and Durons), it runs on a 2x multiplier which is why it shows as 200MHz (100MHz x 2). That's normal.

[red]The system bus is the main part of the system.[/red] All other busses (memory and frontside) are running either at the same speed or using a multiplier of some kind.

With a frontside bus of 200MHz, your system bus is likely at 100MHz. The memory bus in turn is probably at 133MHz using a multiplier that's at a ratio of 100. That's inefficient of course (causing a bit of latency), but hey it works!


~cdogg
[tab]"All paid jobs absorb and degrade the mind";
[tab][tab]- Aristotle
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[KiloZ]

cdogg,
I see what you mean; that makes perfect sense. A friend of mine built this system for me about 4 years ago and at the time it seemed like it was the fastest thing around. But I look at the systems today and soon realize that I'm quite out of date. I've just been tweaking it without spending any money, when possible, to help keep up.
I want to build a new system for myself as soon as $$$ becomes available. Armed with the information you all have provided just in this little thread will help me in determining what kind of motherboard to look for in the future. I do a lot of work on my computer; from live musical multi-track recordings (I use a SoundBlaster Audigy), to office-style work, to intensive 3D gaming. So my aim will be to build an "all-around" sweet system.

Thank you to you all.

All great accomplishments were once considered impossible.

 

[micker377]

cdogg:

<As a matter of fact, it only applies to models that use a 333MHz FSB or higher.>

I have both an IWill (KK266 AMD 1700) and an ECS (KS75A AMD 2200) that wouldn't recognize full speed until I put in DDR. This is even stated in the IWill manual. These mobo's have slots for SDRam and DDR.