Choosing your Ram

[So]

The ram market is fairly simple at the moment (much easier than the days when we had SDRAM, DDR, and RDRAM going at the same time).

When choosing your ram, ask yourself a few questions:

What is the RAM does my CPU & Motherboard support?

• For the Majority of users, this is DDR ram, older P4's may use RDRAM, Athlons of the Thunderbird era and older (i.e. the non performance rated Athlons) likely use PC133 SDRAM. If you have a laptop, you need laptop SODIMMS

• Athlon 64s and current generation P4s use PC3200 DDR ram.

What about CAS latency? Don't I need fast ram for game performance?

• No. The difference between CAS 3 and CAS 2 ram today is nearly trivial. GAMERS: Save money on ram and buy the next level better video card. Already have a 6800 Ultra? Buy a faster CPU, or an MX Duo. You'll get a lot more value for your money.

Are you going to overclock?

• If you are, you may think that you need low latency ram. You don't. Most good quality, brand name ram today has a bit of headroom. If you are really concerned buy PC 3500. Once again, 'fast' PC3200 will be worse and cost more, and 'fast' PC3500 will, once again not give you much for your money.

What about dual channel?

• For a P4, dual channel does give a bit of a performance boost, but it has less of an impact on the AMD side of the fence. In fact, if you're getting a socket 754 Athlon64, there are no dual channel boards available. What does this mean to you? Not much. Socket 754 Athlon 64 rigs are still a great bang for your buck and don't suffer from memory bandwidth problems anyway, so don't sweat it.

Okay, so what should I get?

• Well, that's pretty simple, you probably should get 1 Gigabyte of CAS 2.5 value PC3200. I'd get two stick of this Corsair stuff. If you're overclocking, consider PC3500.

The fact is, RAM timings have relatively little impact on game performance, especially on athlon 64s.

Anyone have anything to add? Discuss and I will be glad to amend the post to make it more accurate and to cover questions not answered already.

 

[Regs]

Only on some over clocks I've seen people forced to raise their timings above stock. But value ram today has tighter timings enough to assure great performance for a good price. This is why I recommend 2.5 cas value ram, since you have a .5 buffer and on other timings just in case your ram does not make the cut on the over clock. But this could all be superseded if you buy RAM that will be rated for your over clock. Which means PC3500 Value ram instead of PC3200 XMS LL and all the trimmings.

So yes, fully agree.

 

[So]

Well, glad to hear I'm not too off the mark...

Mods, is this perhaps sticky-worthy?

 

[So]

Originally posted by: Homerr
I did some testing a couple of weeks ago:

I wanted to see the CAS timings of 2.0 vs. 2.5 on my system by pulling one stick out, then the other. My system also overclocks 10% easily. My wireless network and Norton AV were disabled during testing.

I currently have 2 x 512mb of RAM, but 2 different types:

Corsair XMS Extreme Memory Speed Series 184 Pin 512MB DDR PC-3200
Cas Latency: 2-3-3-6 1T
$118 currently

Taken from Corsair's website:

These parts support 2-3-3-6 latency on Intel platforms, and 2.5-3-3-6 latency on AMD platforms.

The other:

Corsair Value Select 184 Pin 512MB DDR PC-3200
Cas Latency: 2.5
$83 currently

System specs:

Athlon64 3000+ (2.0ghz stock, 2.2ghz OC'd)
Asus K8V Deluxe
9800 Pro
2x 36gb Raptors in RAID 0
1x 250gb Hitachi
1x 80gb WD800JB
Windows XP Pro


CPU-Z says on timings:

XMS (auto): 2.5-3-3-8-11-16 Auto settings in BIOS
XMS (manual): 2-3-3-6-11-16 Manual settings in BIOS
XMS (manual, 2.2ghz): 2-3-3-6-11-16 Manual settings in BIOS, 10% overclock
Value Select (auto): 2.5-3-3-8-11-16 Auto settings in BIOS
Value Select (manual, 2.2ghz): 2-3-3-6-11-16 <does not boot>
Value Select (auto, 2.2ghz): 2.5-3-3-8-11-16 Auto settings in BIOS, 10% overclock
Both sticks (auto): 2.5-3-3-8-11-16 Auto settings in BIOS
Both sticks (auto, 2.2ghz): 2.5-3-3-8-11-16 Auto settings in BIOS, 10% overclock


Super Pi:
1m digits

44 seconds XMS (auto)
44 seconds XMS (manual)
40 seconds XMS (manual, 2.2ghz)
44 seconds Value Select (auto)
40 seconds Value Select (auto, 2.2ghz)
45 seconds Both sticks (auto)
40 seconds Both sticks (auto, 2.2ghz)


PCMark2004

3969 XMS (auto)
3980 XMS (manual)
4376 XMS (manual, 2.2ghz)
3970 Value Select (auto)
4343 Value Select (auto, 2.2ghz)
4003 Both sticks (auto)
4365 Both sticks (auto, 2.2ghz)


Prime95 version 23.8, RdtscTiming=1

XMS (auto):
Best time for 384K FFT length: 23.205 ms.
Best time for 448K FFT length: 27.830 ms.
Best time for 512K FFT length: 31.251 ms.
Best time for 640K FFT length: 39.571 ms.
Best time for 768K FFT length: 48.183 ms.
Best time for 896K FFT length: 58.325 ms.
Best time for 1024K FFT length: 65.528 ms.
Best time for 1280K FFT length: 87.700 ms.
Best time for 1536K FFT length: 104.800 ms.
Best time for 1792K FFT length: 127.801 ms.
Best time for 2048K FFT length: 143.805 ms.

XMS (manual):
Best time for 384K FFT length: 23.207 ms.
Best time for 448K FFT length: 27.864 ms.
Best time for 512K FFT length: 31.139 ms.
Best time for 640K FFT length: 39.546 ms.
Best time for 768K FFT length: 48.252 ms.
Best time for 896K FFT length: 58.220 ms.
Best time for 1024K FFT length: 65.705 ms.
Best time for 1280K FFT length: 87.544 ms.
Best time for 1536K FFT length: 104.530 ms.
Best time for 1792K FFT length: 127.201 ms.
Best time for 2048K FFT length: 143.515 ms.

XMS (manual, 2.2ghz):
Best time for 384K FFT length: 21.046 ms.
Best time for 448K FFT length: 25.207 ms.
Best time for 512K FFT length: 28.415 ms.
Best time for 640K FFT length: 35.923 ms.
Best time for 768K FFT length: 43.832 ms.
Best time for 896K FFT length: 53.056 ms.
Best time for 1024K FFT length: 59.610 ms.
Best time for 1280K FFT length: 79.703 ms.
Best time for 1536K FFT length: 94.932 ms.
Best time for 1792K FFT length: 116.111 ms.
Best time for 2048K FFT length: 130.992 ms.

Value Select (auto):
Best time for 384K FFT length: 23.137 ms.
Best time for 448K FFT length: 27.820 ms.
Best time for 512K FFT length: 31.245 ms.
Best time for 640K FFT length: 39.509 ms.
Best time for 768K FFT length: 48.135 ms.
Best time for 896K FFT length: 58.157 ms.
Best time for 1024K FFT length: 65.540 ms.
Best time for 1280K FFT length: 87.862 ms.
Best time for 1536K FFT length: 104.755 ms.
Best time for 1792K FFT length: 127.426 ms.
Best time for 2048K FFT length: 143.797 ms.

Value Select (auto, 2.2ghz):
Best time for 384K FFT length: 21.114 ms.
Best time for 448K FFT length: 25.386 ms.
Best time for 512K FFT length: 28.418 ms.
Best time for 640K FFT length: 36.036 ms.
Best time for 768K FFT length: 43.885 ms.
Best time for 896K FFT length: 53.074 ms.
Best time for 1024K FFT length: 59.671 ms.
Best time for 1280K FFT length: 79.667 ms.
Best time for 1536K FFT length: 95.146 ms.
Best time for 1792K FFT length: 116.107 ms.
Best time for 2048K FFT length: 131.284 ms.

Both sticks (auto)
Best time for 384K FFT length: 23.146 ms.
Best time for 448K FFT length: 27.803 ms.
Best time for 512K FFT length: 31.158 ms.
Best time for 640K FFT length: 39.435 ms.
Best time for 768K FFT length: 48.036 ms.
Best time for 896K FFT length: 58.165 ms.
Best time for 1024K FFT length: 65.504 ms.
Best time for 1280K FFT length: 87.564 ms.
Best time for 1536K FFT length: 104.516 ms.
Best time for 1792K FFT length: 127.068 ms.
Best time for 2048K FFT length: 143.468 ms.

Both sticks (auto, 2.2ghz):
Best time for 384K FFT length: 21.087 ms.
Best time for 448K FFT length: 25.309 ms.
Best time for 512K FFT length: 28.394 ms.
Best time for 640K FFT length: 35.896 ms.
Best time for 768K FFT length: 43.713 ms.
Best time for 896K FFT length: 52.946 ms.
Best time for 1024K FFT length: 59.577 ms.
Best time for 1280K FFT length: 79.624 ms.
Best time for 1536K FFT length: 95.084 ms.
Best time for 1792K FFT length: 115.647 ms.
Best time for 2048K FFT length: 130.551 ms.

Conclusion:

Corsair XMS and Value Select RAM perform more or less exaclty the same either at stock timings or overclocked. This is on an Athlon64, Pentium 4's probably would be different.

Homerr, if you object to me posting this PM me.

 

[desertfox04]

I second the call for a sticky.

 

[Delorian]

thirds for sticky

definitely a good post as I've seen too many "what ram should I buy" posts coming up lately and this does help explain the "needs" for new builders.

 

[Chronoshock]

Good post So, I was wondering about faster memory, is it worth it to go for pc4000 ram right now and also, how does running pc4000 in 5:4 compare to 1:1

 

[So]

Originally posted by: Chronoshock
Good post So, I was wondering about faster memory, is it worth it to go for pc4000 ram right now and also, how does running pc4000 in 5:4 compare to 1:1

How much of an overclock are you going for? I can't imagine an overclock that'd need it, especially considering that a64 systems aren't really bandwidth starved anyway, 250mhz fsb seems a bit like overkill, and (someone call me on this if I'm wrong) but I don't think theres much of a chance of getting that FSB on an intel system.

 

[ponyo]

Originally posted by: So

Originally posted by: Chronoshock
Good post So, I was wondering about faster memory, is it worth it to go for pc4000 ram right now and also, how does running pc4000 in 5:4 compare to 1:1

How much of an overclock are you going for? I can't imagine an overclock that'd need it, especially considering that a64 systems aren't really bandwidth starved anyway, 250mhz fsb seems a bit like overkill, and (someone call me on this if I'm wrong) but I don't think theres much of a chance of getting that FSB on an intel system.

Both Intel and AMD systems can hit 250+. However you'll find lot more Intel systems hitting 250+. 250fsb is really nothing now. 300 is where overclockers are shooting for now.

 

[SonicIce]

Someone should make one of these for other components too like moniters or speakers or motherboards or hard drives. very insightful, So.

 

[edumacated81]

Nice post! I've had Corsair XMS PC3200C2 512 for a while...great stuff. Just ordered a Gig a few days ago. Corsair is great ram all around...spend the few extra dollars and get good ram

 

[So]

Glad to hear you guys liked my post. :beer:

Maybe we can sticky it so that there are less RAM threads every day

 

[So]

Originally posted by: Naustica

Originally posted by: So

Originally posted by: Chronoshock
Good post So, I was wondering about faster memory, is it worth it to go for pc4000 ram right now and also, how does running pc4000 in 5:4 compare to 1:1

How much of an overclock are you going for? I can't imagine an overclock that'd need it, especially considering that a64 systems aren't really bandwidth starved anyway, 250mhz fsb seems a bit like overkill, and (someone call me on this if I'm wrong) but I don't think theres much of a chance of getting that FSB on an intel system.

Both Intel and AMD systems can hit 250+. However you'll find lot more Intel systems hitting 250+. 250fsb is really nothing now. 300 is where overclockers are shooting for now.

Interesting, now see, I thought that Mobile Athlons were where it was at, shows how out of date I am on overclocking. I assume that P4's can lower their multiplier now then.

 

[MattTrubac]

Hey,

I'm kind of a newbie to hardware configuration- just joined the forum tonight. I've assembled my own systems for a while now but have never really gotten into the technical aspects of it. Maybe because I've never messed with Over Clocking (I use my system for professional video editing and rely on a stable system). I have a few questions though.

What is the 250mhz FSB that is being discussed? I was under the impression that my P4 2.8e had an 800mhz FSB.

I have 2 sticks of 512mb UNB PC3200 CL3 Apacer memory. I bought them about 8 months ago at my local computer shop. Asked for PC3200 memory and it is what they gave me. In the bios of my intel D865PERL m/b should I set the SDRAM Frequency to 400mhz? I've been reading of people getting their PC3200 memory to 200-somethingmhz but think this refers to the bus speed between the CPU and Memory (or something similar) and not the actual memory clock speed. Am I correct?

The system I am currently working on is used strictly for professional video editing and has been giving me problems lately. But I think those issues are for a different post or maybe some searching.

 

[MattTrubac]

Additional note...

If I set the SDRAM Frequency to Auto the Intel Desktop Control Center displays it at 266MHz. Why would this be? Can it not auto-detect PC3200/DDR400?

 

[ts3433]

Matt,

The FSB on P4's is quad-pumped, so the 800 MHz FSB is its effective speed--it actually runs at 200 MHz by default.

Your PC3200 memory should be running at a clock speed of 200 MHz (DDR, so 400 MHz effective speed). Overclocking that PC3200 to 266 MHz (DDR533=something like PC4300) will almost certainly bring problems, if it doesn't just fry the RAM.

 

[MattTrubac]

Thanks for the response.

The only options in the bios are...

Auto
266MHz
320MHz
400MHz


when I select Auto the Intel Desktop Control Center displays 266MHz.

Is 266MHz what it should be or should I select 400MHz manually?

Earlier I chose 400MHz and ran the Intel Desktop Control Stress tests for Memory, CPU, and MMX all at 100% with 0 errors.

System Temp Zone 2 (which I believe is around the memory reached 60C and the CPU held steady around 70C. The test ran for fifteen minutes straight with the CPU maxed out at 100.

Thanks,
Matt

 

[Tostada]

Originally posted by: MattTrubac
Thanks for the response.

The only options in the bios are...

Auto
266MHz
320MHz
400MHz

If that's the case, then it's obviously talking about the effective speed. Actual MHz would be 133, 160 (that's odd...) and 200. 200 MHz = DDR400 = PC3200.

 

[cw42]

what's the clock&amp;folder thing at the title of this thread??

 

[So]

Originally posted by: cw42
what's the clock&amp;folder thing at the title of this thread??

It's stickied to the top of the forum, so it remains visible. Check the Hot Deals forum and see how many threads are locked and stickied there.

 

[Chaotic42]

You need to have ECC and Registered memory stuff on there.

From Crucial-

Registered: DDR and SDRAM can be unbuffered or registered. EDO and FPM can be buffered or unbuffered. Buffered modules contain a buffer to help the chipset cope with the large electrical load required when the system has a lot of memory. Registered modules do not have a buffer but do contain a register that delays all information transferred to the module by one clock cycle. Buffered and registered modules are typically used only in servers and other mission-critical systems where it is extremely important that the data is properly handled.

ECC: What is error correction?
In digital electronic systems, information is represented in binary format (1's and 0's). When binary information is passed from one point to another, there is always some chance that a mistake can be made; a 1 interpreted as a 0 or a 0 taken to be a 1. This can be caused by media defects, electronic noise, component failures, poor connections, deterioration due to age, and other factors. When a bit is mistakenly interpreted, a bit error has occurred.

Error correction is the process of detecting bit errors and correcting them and can be done in software or hardware. For high data rates, error correction must be done in special-purpose hardware because software is too slow.


From here.

 

[trexpesto]

Someone posted that they didn't get the first post here, so I tried to lay it out a little differently for them. They were wondering what to get for overclocking. I agree with the first post, but wanted to explain a little how and why. Some is a repeat of what the first post said. This applies to AMD, for Intel you can get more expensive higher-frequency RAM.

First figure out what OC is your target by looking at other people's results.
Be realistic! Perhaps take an average of what you see, consider whether they have better CPU steppings, etc.

The speed of the machine is the result of the Front Side Bus speed times the CPU multiplier.
Whatever FSB you are shooting for in that overclock, you try to get RAM that will match that with a 1:1 ratio.
That ratio is FSB:RAM. Running 1:1 means they are running at the same speed, which is more efficient.

An example:
PC 3200 = DDR 400MHz. In other words it is guaranteed to run at 1:1 with a 200 FSB. (Since it is Double Data Rate, you divide 400MHz by 2. 200:200 == 1:1)

Most good brand RAM is overclockable to some degree, so usually you will be able to get it to run at a higher FSB than it is rated, it's just not guaranteed by the manufacturer.

For instance I bought PC 3500 DDR 433MHz to run 1:1 with my target FSB of 216-217. Works great, but I could have probly got PC3200 and oc'ed it to 216. It would have been cheaper.
I was (ok, I am) a noob and didn't want to take a chance on stability problems because I have to do my work on this box. For a gaming machine, you won't be losing income if you crash. Unless your games are online casino games maybe.

Sometimes when overclocking your RAM you may need to increase the VDIMM (voltage supplied to the RAM) and/or you may need to relax your timings so that it will be able to in keep up with your FSB while maintaining 1:1 ratio. By relaxing your timings I am referring to raising the CAS numbers of the RAM in the BIOS. They are numbers like 2.5-3-3-6. The lower the numbers the faster the RAM, and the more expensive. There is some insight into those numbers on the Mushkin site, among other places. There are also many guides to overclocking your RAM like http://www.overclockers.com/tips1039/. If the jump in FSB is too much for the RAM to take at 1:1, like you are trying to run PC 2100 at 216 FSB, then you can run the ratio at 5:4, 4:3 or whatever, if your motherboard and BIOS support it.

Once you decide on a speed, you can try to find a particular stick. Good brands I have heard about are Corsair, Mushkin, Kingston, OCZ, maybe Geil.

Look around to see if the brands you are thinking about have problems being compatible with that MB. Apparently some matchups of mobo and RAM don't like to overclock as well, or to work in dual channel as often, but some of that could be luck of the draw and rumor. The memory manufacturer web site may list the motherboards that it has been tested with, so that's be a good sign, but it doesn't rule out other boards. You can pay more for a "kit", 2 modules that have been tested together that are guaranteed to run in dual channel, but usually 2 of the same sticks will work just fine.

CAS 2.5 is generally the best for the money now. You may not notice the difference between it and CAS 2. CAS2.5 Corsair Value Select PC3200 is ~ $77 for 512MB at newegg. So is Mushkin Green CAS 2.5. Others, dunno. You want a gig. Can you get it to run at the FSB you want? Newegg reviews may have some stats...

Go forth and multiply.

Edit: Generally you will do your memory OC after seeing what you can get with your CPU. It can be worth it to run at a ratio which is not 1:1, depending on what fsb you can get and what you are doing with your machine. You can test your memory with memtest, windows memtest, and Prime95. Running Prime95 Stress Test for hours without errors is the standard of determining system stability. I run it overnight after I know my HSF is adequte.

 

[KDOG]

I've had a gig of Corsair XMS PC3200 CL2 in my system for about 6 months. But recently I've taken one of the 512MB sticks OUT of my machine. The reason? Well, I have an Asus A7N8X nforce2 Ultra 400 and it can run dual channel memory, but when I'd run the SiSoft Memory benchmark guess what? There was NO difference in the benchies between single and dual channel. Besides I have another nForce 2 Ultra 400 mobo mATX Chaintech in an Antec Aria that needed some good memory

 

[Alkaline5]

Originally posted by: KDOG
I've had a gig of Corsair XMS PC3200 CL2 in my system for about 6 months. But recently I've taken one of the 512MB sticks OUT of my machine. The reason? Well, I have an Asus A7N8X nforce2 Ultra 400 and it can run dual channel memory, but when I'd run the SiSoft Memory benchmark guess what? There was NO difference in the benchies between single and dual channel. Besides I have another nForce 2 Ultra 400 mobo mATX Chaintech in an Antec Aria that needed some good memory

I've been running single-channel 512MB Corsair Value for the last year and recently added another stick for dual-channel. Most games and apps saw only minimal performance increase except for Doom3 where I got over a 15% increase in timedemo framerate (35.7fps -> 42.9fps). According to Anand's memory tests with D3, moving from 512MB dual-channel to 1GB dual-channel had little effect on their A64/P4 test systems, so the gains I saw should be attributable to moving to dual-channel (and not just the additional RAM). I was quite surprised to see dual-channel memory finally improve performance on something on an AXP platform.

 

[trexpesto]

Originally posted by: KDOG
I've had a gig of Corsair XMS PC3200 CL2 in my system for about 6 months. But recently I've taken one of the 512MB sticks OUT of my machine. The reason? Well, I have an Asus A7N8X nforce2 Ultra 400 and it can run dual channel memory, but when I'd run the SiSoft Memory benchmark guess what? There was NO difference in the benchies between single and dual channel. Besides I have another nForce 2 Ultra 400 mobo mATX Chaintech in an Antec Aria that needed some good memory

maybe it wasn't running in dual channel then? Was it a DC kit? How do you tell for sure? I would think doing what you did should be the best way to show it was Not running DC...

EDIT: Point taken about quantity. 512 will do fine for most games out there. I have to do work on this thing, so I run sql swerver, netbeans, as well as Weblogic, and huge client apps, so I still swap out. XP can take up to 200Mb by itself if I let it.....