ABXZone Computer  Forums



 
 
Thread Tools Display Modes
Old 08-07-2003, 07:32 PM   #1
specmike
Yes, Yellowbeard
 
specmike's Avatar
 
Join Date: Oct 2002
Location: Metro Atlanta, GA.
Posts: 2,647
Post A Noob's Guide to Selecting RAM and a CPU written by a Noob

(I typed this aimed at a buyer that knows about the same or less than I did when I first started coming in here, virtually nothing. Please, veterans and gurus, offer up any corrections or additional advice.)

On most if not all of the new Canterwood/Springdale chipset boards, or 875/865 if you prefer, the ratios offered are 1:1, 5:4, and 3:2. The reason for this is that Intel P4 CPUs have a locked multiplier. The multiplier is a number assigned to that CPU by Intel

The current P4s run at an internal clock speed of 200mhz. Intel "quad pumps" that thru the CPU which is where we get the 800mhz FSB, 200 X 4. The multiplier is the factor that determines the external speed of the CPU. For example, on my P4 2.4c, my multiplier is 12. 12 x 200mhz = 2.4ghz. A 2.6 CPU has a multiplier of 13, 2.8 has 14 and so on. On an equivalent Athlon CPU, the multiplier is not locked. To overclock, you can manually change this number to get higher clock speeds and/or higher RAM frequencies.

Intel does not like or allow this so that's where the RAM ratios come into play. Since you can't change the multiplier, each step change of the CPU FSB results in a given linear change of the RAM freq. The MOBO makers have made it where the OCing user can select a ratio that will allow higher OCs. Thus, the choices of 1:1 which is default, and 5:4 and 3:2. The 5:4 and 3:2 ratios make each step increase of the FSB effect the RAM less. This allows higher FSB with existing RAM.

The ratios are basic math. Obviously a 1:1 ratio will yield a 200FSB and a RAM frequency of 200, 205 = 205 etc. However, since Dual Data Rate RAM transfers data on the rise and fall of each cycle (each half of the sine wave for those more technically inclined) you actually get data X 2 or DDR400 at FSB200.

A 5:4 ratio is figured like this. Example: FSB 250 divided by the first number of the ratio, the CPU factor of 5.....250/5 = 50. You then multiply the memory factor of 4 by 50.....4 X 50 = 200 or DDR400. A 3:2 is for example FSB200/3 = 66.6 X 2 = 133.2 or DDR266.

This is important since right now our CPU speeds are sort of "outrunning" our RAM. What I mean by this is that we have P4s out there but there that are approaching a FSB of 300 when OCd! That is DDR600 People that are running their FSB that high are using a 5:4 or a 3:2 ratio. 300/5 = 60 X 4 = 240 or DDR480. 3:2...300/3 = 100 X 2 = 200 or DDR400.

All you have to do is find a CPU that will do it and risk smoking the little fella. There is no RAM out there that will run FSB300 @ a 1:1 ratio or PC4800. I'm sure Corsair, OCZ, Geil, Kingston, et al are working on it though.( DDR2 will be out soon and it will start at DDR533 or PC4300. )

I have not seen bios screen shots on other MOBOs but the current Asus boards are using a bios from American Megatrends Inc. In their bios, you choose a ratio by either selecting DDR400, DDR333, or DDR266. That is what freq. the RAM will run at if you choose a FSB of 200. Each speed actually represents a ratio, DDR400/1:1, DDR333/5:4, and DDR266/3:2. When you change the FSB it changes the RAM frequency a given amount depending on which option you have chosen.

What confuses many, (including me initially) is that the bios screen does not change the DDR freq. you see. It stays at either 266, 333, or 400. You have to do a little math like above to figure your OC. It will get to the point that you will know them automatically if you tweak much. 1:1 is the easiest, it's basically FSB X 2. So FSB200 = DDR400, FSB217 = DDR433(434 actually when you round it) FSB233 = DDR466, FSB250 = DDR500 and on and on. We'll need to learn more math as the technology increases.

So here is my take on buying a new Canterwood/Springdale based board. Part of this works on the assumptions that a. the 1:1 ratio is the best to use on these boards and b. that users have a Springdale based board that will allow the activation of PAT.

This may get a bit lengthy or boring:ZZZ: but I did not force you to click this link

With the release of the PC3700 and PC4000 DIMMs, many are asking about proper combinations of RAM+CPU. Normally you would think that the fastest RAM going and the fastest CPU going would be the BEST combination, cost not withstanding.

But, it seems that this is not the case. To fully utilize PC3700 RAM on current P4c CPUs and on the current Intel 875/865 chipsets, you must run the RAM at a 1:1 ratio according to the benchmarks I have seen. Some debate the validity of synthetic benchmarks and say they prove nothing. If that is your belief, then don't buy any RAM above DDR400. The 5:4 ratio is not as good as the 1:1 as far as overall memory bandwidth which is why we buy good fast RAM.

Back to the point, the FSB for PC3700 (DDR466) at a 1:1 ratio is FSB233 and FSB250 for PC4000 (DDR500). This means that you have to be able to overclock (OC) your CPU to run the RAM at its stock speed. To OC the RAM past stock, you REALLY have to OC your CPU. Prometheus, big toe, Eva2000, et al are getting some fantastic numbers with the newest RAM out, check out their posts for more details.

Well Hawk, a frequent poster here and Master of all that Matters over at the BleedinEdge has tested retail samples of all 5 issues of the P4c CPUs. He has found the following:
P4 CPU Speed Stock MAX FSB
2.4c 288FSB
2.6c 270FSB
2.8c 266FSB
3.0c 247FSB
3.2c 238FSB

His results are exceptional and he knows how to get speed out of a rig. One of his nic names is "Overclocking Junkie" and it fits. The reason I am posting all of this is to show that you can't necessarily utilize the DDR466 and DDR500 RAM with EVERY CPU available. So, for any of you that are considering a new rig, consider your CPU choices.

Hawk's results are not etched in stone however so buy whatever CPU floats yer boat. For example, the Goog @ Corsair HoH stated recently that he has run 2 3.0s. One would go over 250FSB, one would not so it is a hit and miss. It is always hit and miss with OCing but so far, the 2.4c CPUs are the most consistant at hitting high FSB.

On the other end of the spectrum, if you want the MAXIMUM performance at box stock speeds, I'd say go with the good PC3200 RAM that will do TIGHT timings + a 3.2ghz CPU. Then, you are running fantastically high and don't have to worry with any OCing. Some users want TIGHT timings, some want HIGH FSB, some want a good balance of both.

Now, as to timings, I can attest that with my results + posts I've seen by Hawk et al, the PC3700 and PC4000 stix do NOT need tight timings to have AWESOME results. Good stock PC3200 is far better on a dual channel MOBO than any previous single channel MOBO but the PC3700 and PC4000 with more loose timings are EVEN BETTER. IMO, FORGET about tight timings unless you are running an AMD CPU.

So here are my rules of thumb for buying an 875/865 based board and CPU+RAM. If you can't hit a 233FSB, you will be underclocking the PC3700 and PC4000. If you can't hit a 250FSB you will be underlocking the PC4000.

1. If you don't want to OC and want to run stock CPU speed with TIGHT RAM timings buy the good PC3200 or PC3500 and the FASTEST CPU you can afford.
2. If you want a MILD OC with TIGHT timings, buy the BEST PC3500 and the FASTEST CPU you can afford.
3. If you want a MEDIUM OC your BEST buy would be the PC3700 with the FASTEST CPU YOU BELIEVE WILL HIT A 233 FSB. I am on the fence at this point with a 2.8c, will they consistently hit a FSB233? Buy one and let me know
4. If you want a HOT OC and want to go all out, buy the PC4000 and either a 2.4c or 2.6c. My choice is the w2.4c. It's not as "slow" as it sounds and you can spend the money you save on the lovely PC4000 Anyways, a 2.4c at FSB 250 is 3.0ghz, how much faster do you wanna go?

It seems to me the cap on the P4c CPUs is about 3.6ghz due to architectural limitations. This is still RARE and again, hit and miss. Do you want to play hit and miss with a $700 3.2ghz CPU? A 3.2 at 3.6 is only a FSB222 which is hard to get on a 3.2c. I have seen several people post that they cannot hit 220 on a 3.2c.

Since 3.6 is about the average cap on the P4 Northwood architecture, OCing it up to or past 3.6 is tough. The headroom of a 2.4c is its strength. All P4c CPUs are from the same die, and are just speed binned. The "best" chips become 3.2s and the "worst" become 2.4s. I've had my 2.4c at 3.0 on stock voltage so that tells you how "bad" a 2.4c is. IMO, save the money on a CPU and buy better faster RAM!

I have based a great deal of this on what I have observed so I may be wrong on some points. Also, I have based this on observations of benchmarks. Some argue the validity of benchmarks and what they “really” mean. However, many buyers base their purchasing decisions on published benchmarks and subsequent satisfaction based on their own marks. I think the published benchmarks in this forum are valid for these reasons.
1. They are end user equipment bought retail, except as noted. I believe people here are honest and fess up when they are using beta or sample units. Why lie here?
2. They are valid because regardless of what they “really” mean to the end user, they are the same marks and can be used to compare relative performance. Will the consumer ever see the difference in Sandra 5978/5997 and 6011/6046? Not with the naked eye but when they run their own benches, they will get some measure of how they match up to similar equipment and hopefully get some satisfaction of getting their money’s worth. If not, they can always RMA. Well, there it is, fire away!

spec "I'm out of work and have nothing to do but hang out here" mike
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CORSAIR TECH SUPPORT
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
(Offline)  

Advertisement [Remove Advertisement]
Old 08-07-2003, 07:52 PM   #2
CrocHammer
Croc - OlderOvercrocker
 
CrocHammer's Avatar
 
Join Date: Feb 2003
Location: Surrey, BC
Posts: 1,345
Great job for a Noob or non-Noob. Hell great job, period.

By the way the Asus ( and I thought other boards ) is 320mhz @ 5:4. It happens a lot.

I am thinking.....Sticky????



__________________
C2D6600 on Asus P5B Deluxe with ArcticCooling Pro7 heatsink fan
EVGA 8800GTS with Samsung 226BW
4 x 1024 Mushkin HP2-6400
1XS. Barracuda 640 gig 7200.11
2 x S. Barracuda 320 gig 7200.10 in RAID O
LG sATA DVD/RW
Logitech G5 Laser mouse & G11 keyboard
Corsair HX-520 watt modular PSU
Lian-li PC60U -updated mod & lighting
4 x 80mm inlet and 2 x 80mm exit fans on Hexus fan controller
(Offline)  
Old 08-07-2003, 07:52 PM   #3
iMogal
Zoom Zoom...
 
iMogal's Avatar
 
Join Date: Oct 2002
Location: Canada
Posts: 1,226
Nice rundown! :wave2:

I'll add this one to my notes....
__________________

SilverStone TJ-08
MAXIMUS VI GENE mATX
Intel® Core™ i7-4770K Processor (8M Cache, up to 3.90 GHz)
2x4Gb G.SKILL TridentX F3-2400C10D-8GTX 8GB 2X4GB DDR3-2400 CL10
OCZ Vertex 3 - 128Gb
WD1001FALS Caviar Black 1TB
AMD Radeon HD 7950 GPU
Corsair HX620 Modular PSU
Dell UltraSharp 2407FPW (x2)
Monsoon MM-700 2.1 Speakers
__________________
(Offline)  
Old 08-07-2003, 08:04 PM   #4
specmike
Yes, Yellowbeard
 
specmike's Avatar
 
Join Date: Oct 2002
Location: Metro Atlanta, GA.
Posts: 2,647
Quote:
Originally posted by CrocHammer
Great job for a Noob or non-Noob. Hell great job, period.

By the way the Asus ( and I thought other boards ) is 320mhz @ 5:4. It happens a lot.

I am thinking.....Sticky????



You are correct Croc, I have been told why that is. Anyone care to refresh me? In my "prescription drug induced so I won't feel the pain in my soon to be surgically repaired neck" haze, I can't remember why that is. But hey, it's only a measly 13mhz.

Mike.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CORSAIR TECH SUPPORT
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
(Offline)  
Old 08-07-2003, 08:07 PM   #5
CrocHammer
Croc - OlderOvercrocker
 
CrocHammer's Avatar
 
Join Date: Feb 2003
Location: Surrey, BC
Posts: 1,345
I can't remmeber why either and it's no biggy.
__________________
C2D6600 on Asus P5B Deluxe with ArcticCooling Pro7 heatsink fan
EVGA 8800GTS with Samsung 226BW
4 x 1024 Mushkin HP2-6400
1XS. Barracuda 640 gig 7200.11
2 x S. Barracuda 320 gig 7200.10 in RAID O
LG sATA DVD/RW
Logitech G5 Laser mouse & G11 keyboard
Corsair HX-520 watt modular PSU
Lian-li PC60U -updated mod & lighting
4 x 80mm inlet and 2 x 80mm exit fans on Hexus fan controller
(Offline)  
Old 08-07-2003, 09:29 PM   #6
NeoXtremeX
The_Ace
 
NeoXtremeX's Avatar
 
Join Date: Aug 2003
Location: Santo Domingo
Posts: 957
Exactly what i (and many people) were looking for. *period*.
(Offline)  
Old 08-07-2003, 09:59 PM   #7
Panama Red
1st Log...just a memory
 
Join Date: Jun 2003
Location: near the left coast of Michigan
Posts: 609
WOW! Excellent work, Mike. You've taken a complicated and often confusing subject and broken it down so even us REAL Noob's can make sense of it. All it takes now is an understanding of some basic math principles. Too bad for the folks that slept thru those boring Algebra lectures, eh?
(Offline)  
Old 08-07-2003, 10:21 PM   #8
specmike
Yes, Yellowbeard
 
specmike's Avatar
 
Join Date: Oct 2002
Location: Metro Atlanta, GA.
Posts: 2,647
Quote:
Originally posted by Panama Red
WOW! Excellent work, Mike. You've taken a complicated and often confusing subject and broken it down so even us REAL Noob's can make sense of it. All it takes now is an understanding of some basic math principles. Too bad for the folks that slept thru those boring Algebra lectures, eh?
I still either need an abacus or to take my shoes off. That's why I went P4 instead of AMD, too much math
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CORSAIR TECH SUPPORT
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
(Offline)  
Old 08-08-2003, 02:13 AM   #9
vegetto34
Registered User
 
Join Date: May 2003
Location: Texas
Posts: 60
Re: A Noob's Guide to Selecting RAM and a CPU written by a Noob

Quote:
Originally posted by specmike
( DDR2 will be out soon and it will start at DDR533 or PC4300. )
Wrong. PC4200.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
(Offline)  
Old 08-08-2003, 02:44 AM   #10
SubZero
Moderator
 
Join Date: Feb 2001
Location: Below sealevel
Posts: 9,668
A post with so much effort in it deserves a sticky!! Good post!
__________________
Gigabyte Gigabyte GA-Z77X-UD5H iZ77 | Intel i7-3770K | eVGA 670 GTX FTW | 16GB Corsair Vengeance | 2x Samsung 840 Pro SSD | Corsair GS700 PSU
(Offline)  
Old 08-08-2003, 06:16 AM   #11
punchy501
Registered User
 
Join Date: Aug 2003
Location: Brisbane
Posts: 12
Great summation m8!!
I can relate to your obvious enthusiasm for overclocking so well.

July 1 this year I was running an AOPEN AX4B P4 1.8 and two sticks of 256 PC2100. This board allowed a massive BIOS OC to 1.9!! - and that was it as far as my OCing career stood!

That day I was on the net bored :ZZZ: and came across a review of the P4P800 and how ASUS tricked it to behave like it had a 875 chipset - HMMMMMM I thought - and to boot this new upstart board from ASUS was priced as a bargain and seemed to almost outgun the more expensive Canterwood board!

Was I hooked or what? July 4 I had myself a new P4P800, P4 2.8C and a stick of fast Geil 512 DDR433 ram to play with. I'd never put a system together before but thought I could do it easy - it's amazing how forums and general info on the net can make one feel like they have a PHD in computer engineering!!

So I got my new system together and started to discover problems with my Geil ram (well at the time I thought Geil was the problem) and having all sorts of trouble getting this thing to boot or even POST. After some more study at the "Institute of Net Research" I took this ram back and got me some nice low latency Corsair stuff. It was at this time that I discovered (like Christopher Columbus - a new land this and other forums (Bleedingwhatitsname) are an incredible wealth of helpful information!

I soon found out Turbo [enabled] was evil and claimed latencies didn't work :confuse2:. I couldn't work out why my ram kept giving me BSOD at higher FSB's but then learnt about dividers etc etc etc

.... and now I'm having the time of my life and got me a nice stock cooled rig getting a 2.8 to run at 3.35.
But it (the addiction) doesn't stop there - oh no!!! - dumped the Ti4200 didn't I and got me a V9950 FX5900 from ASUS last weekend and doesn't this beauty like to clock from std 400/851 upwards towards 500+/1000

Damn this forum! and I thought everything was sweeeeeeet with TURBO now a friend [enabled] - no more BSOD and PAT enabled --- DAMN what was that thread this week???----- I don't have PAT when O/Cing :bigcry:

Tomorrow with the help of the thread from bigtoe and Radelon and others I will embark on getting PAT back with some ingenious BIOS tweaking ...................it never ends!!!!

Thanks and kudos to everyone
__________________
P4C800-E Deluxe Bios1008
P4 2.8C O/C 3.4 FSB242 1:1 66:33
Corsair 2x512MB XMS3700 DDR466(running@484MHz) 3-4-4-8-4
ASUS V9950 FX5900 @490/890

Thermaltake 480W ATX PSW w/Dual Fan+PFC
Thermaltake Tiger 1 for i875 chipset;
Zalman CNPS5700D-Cu Cooler for CPU

Thermaltake Xaser III 2000A Case

Last edited by punchy501; 08-08-2003 at 06:24 AM..
(Offline)  
Old 08-08-2003, 07:06 AM   #12
Pentium4
Registered User
 
Pentium4's Avatar
 
Join Date: Sep 2002
Location: Adelaide, South Australia
Posts: 393
Thanks specmike, great article. I fall into the 'Tight Timings' list. Makes me feel a little better about having ordered the KHX3200/256 to go with my P4C800-E, and 3.2GHz beastie (if they ever arrive)
__________________
INTEL INSIDE
* Gigabyte GA-Z97X-G7 * Intel i7 4790K * G.Skill 2400MHz TridentX 16Gb DDR3 (10-12-12-31-1T) *
* Samsung U28D590 28" 4K Monitor * Palit GTX780 VGA (967/6010) * Samsung 850PRO 1TB SSD *
* LG CH12LS28 Blu-ray Optical Drive * CM Xornet II Gaming Mouse * Onboard 5.1 Surround Audio *
* Logitech K200 Keyboard * Tt VersaII Mid-Tower Case * SeaSonic XP1000W PSU (100% Modular) *
(Offline)  
Old 08-08-2003, 09:07 AM   #13
specmike
Yes, Yellowbeard
 
specmike's Avatar
 
Join Date: Oct 2002
Location: Metro Atlanta, GA.
Posts: 2,647
Re: Re: A Noob's Guide to Selecting RAM and a CPU written by a Noob

Quote:
Originally posted by vegetto34
Wrong. PC4200.
It' actually a data rate of 4256 so I (logically) rounded up. I guess the industry, or you, says different?

Mike
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CORSAIR TECH SUPPORT
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
(Offline)  
Old 08-08-2003, 10:06 AM   #14
CrackFerret
Registered User
 
Join Date: Aug 2003
Posts: 7
Wait a sec, I have an IC7-G comming soon with 512 kit of kingston pc3200 DDR400, and a 2.4c p4.

Sounds to me that you are saying that if I want to oc to 3gig I should consider getting faster ram and OC at 1:1.

Is it a bad idea to try and reach 3gig with pc3200 memory?

Should I get some pc4000 before OC'ing?

If I read right, a 5:4 ratio means that with a 2.4c and fsb bus at 250 the 2.4 will be OC to 3gig and the memory runs at a stock 400 (when using pc3200). Is this right?

Sorry I'm new to this.

Last edited by CrackFerret; 08-08-2003 at 10:13 AM..
(Offline)  
Old 08-08-2003, 10:44 AM   #15
CrocHammer
Croc - OlderOvercrocker
 
CrocHammer's Avatar
 
Join Date: Feb 2003
Location: Surrey, BC
Posts: 1,345
You got it right. A on your math test
__________________
C2D6600 on Asus P5B Deluxe with ArcticCooling Pro7 heatsink fan
EVGA 8800GTS with Samsung 226BW
4 x 1024 Mushkin HP2-6400
1XS. Barracuda 640 gig 7200.11
2 x S. Barracuda 320 gig 7200.10 in RAID O
LG sATA DVD/RW
Logitech G5 Laser mouse & G11 keyboard
Corsair HX-520 watt modular PSU
Lian-li PC60U -updated mod & lighting
4 x 80mm inlet and 2 x 80mm exit fans on Hexus fan controller
(Offline)  
 


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Powered by vBulletin® Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
vBulletin Skin developed by: vBStyles.com

© 2006 - 2016 ABXZone Forums | About ABX Zone Forums | Advertisers | Investors | Legal | A member of the Crowdgather Forum Community