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DDR2-667 vs DDR2-800

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March 10, 2008 3:40:15 PM

Specs (keep in mind it's an HP)

Q6600 @ stock (locked bios? couldn't find anything for overclocking)
2x1GB DDR2-667 (probably generic since it came with the hp)
Visiontek HD2600XT 512MB (the only part I bought separately)
300GB hard drive
300W some generic brand psu (might replace in 2 years or so when I get a new vid card)
Vista home premium 32-bit

I was thinking of getting 4GB of RAM by buying another 2gb (2x1gb) of 667mhz ram before ddr-3 goes mainstream and ddr2 busts up their prices but some people are telling me it would be better to get 4GB of ddr2-800 brand-name ram instead of 2gb being generic ddr2-667 and the other 2gb being brand-name. Basically, does ddr2-800 make a difference compared to ddr2-667 in gaming? Considering NO OVERCLOCKS! Also, does brand-name make a difference compared to generic as far as performance? My set-up is going to be 1 gb generic | 1gb brand-name (either buffalo or kingston) | 1gb generic | 1gb brand name.

More about : ddr2 667 ddr2 800

March 10, 2008 4:20:34 PM

The only way this matters is if you can run the ram faster then 1:1. Q6600 is ~2400MHz clock. the muliplier is 9 and the system bus is 266 (FSB/4 or 1066/4). DDR2 ram is rated by its "effective" speed. DDR2 800 runs at 400MHz. So a 1:1 with your system is DDR2 533 (266 X 2= ~533) All that said, its important to keep in mind that you may be able to run the ram at a faster ratio then the system speed. Do it if at all possilbe. I have a Q6600 running stock speed and my ram is running at 400MHz or DDR2 800 spec. It is a bios option. If you want to find out how fast things are running and you can't find it in the bios use CPU-Z. http://www.cpuid.com/cpuz.php
a b B Homebuilt system
March 10, 2008 4:27:54 PM

Technically you can run PC533 which would run at a 1:1 ratio. On a stock clock with a Q6600 the bus runs a 266MHz so x2(for DDR) =533. This would be the minimum memory it would support. 667 is the min for 333MHz bus, 800 for 400MHZ, etc.

How this is calculated is there is a memory divider. A 1:1 tends to perform better than ones with a divider. One memory cycle for every cycle of the bus.

In your case you have 667memory on a 266 bus. the divider is 5:4. it is figured out like this. 266*(5/4)=332.5(about 333MHZ) with the x2(DDR) it is 666(aka 667MHZ you can't say 666 because it's evil or some crap like that)

In 800MHz memory on your CPu it would be 266*(3/2)=399(about 400MHz) x2(DDR)= 800MHZ

So really you are using a divider either way and wouldn't really get much of a performance boost from DDR2 800. Maybe if it has lower latency it would be a benefit. You DO want to get identical memory as to what you have or you may have issues.

I'd just get another set of 667MHz memory to be honest.

But I want to comment as well. WHY do you need 4GB anyways? are you having issues? With a 32bit OS you will only see just over 3GB anyways, if that. I only see 3GB with my set. It's because of memory addressing on your Graphics card and other items that are also used for memory. You can't use it all.
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March 10, 2008 4:33:40 PM

A quick note about 1:1. I have run a few benchmarks including a few of my own for intense calculation. Run the memory as fast as it will go. I get better results from running at DDR2 800 spec then I get at DDR2 533 spec. This is without a change in the CPU speed. This is just adjusting the ratio for memory compared to system bus speed.
a b B Homebuilt system
March 10, 2008 4:38:52 PM

hairycat101 said:
A quick note about 1:1. I have run a few benchmarks including a few of my own for intense calculation. Run the memory as fast as it will go. I get better results from running at DDR2 800 spec then I get at DDR2 533 spec. This is without a change in the CPU speed. This is just adjusting the ratio for memory compared to system bus speed.

Just curious though, is it a worth while difference? or just nominal?
a b B Homebuilt system
March 10, 2008 4:46:47 PM

Ok I stand corrected. I did some research on this and take it back. DDR2 800 would give you a slight increase in performance, but I stills say the 667 will do just fine.
a c 84 B Homebuilt system
March 10, 2008 4:51:04 PM

The faster ram only makes a difference in synthetic benchmarks or overclocking. The C2D and quad processors are not very sensitive to memory speeds. In some applications you might see 1-2% difference. In gaming, you will see none, the vga card is much more important. For games, the additional 2gb will make the most difference. How much it helps is determined by how much you need the added ram. Ram is cheap, and it can't hurt; go for it.
March 10, 2008 4:52:29 PM

jay2tall said:
Just curious though, is it a worth while difference? or just nominal?


Worth it to set the ratio. As far as worth the price to get DDR2 800 vs DDR2 667 at the store... I think so. As the prices aren't much different. Actually I notice the difference. Of course, I am running some VERY intense calcs. I don't know if I would notice if I were running office (word, excel, etc.) apps only. I do modeling in CAD and I have to go through some very thorough routines to clean up all of the line work. That can mean processing some very large files. So... just setting the ratio... yea, its easy to do and worth the 10 seconds. Worth the price... yes again from my point of view. I see the prices as pretty close right now... at least for good, name brand sticks.
a b B Homebuilt system
March 10, 2008 5:04:33 PM

I guess then it would depend on what he is doing. Gaming? general use, or calculations or memory intense apps.
March 10, 2008 5:06:07 PM

I think it depends just as much on whether his HP will run his ram at any speed but 1:1. ;) 
a b B Homebuilt system
March 10, 2008 5:40:56 PM

hairycat101 said:
I think it depends just as much on whether his HP will run his ram at any speed but 1:1. ;) 

OH yeah I forgot it was an HP. Boy I love PC Manufactures, they are so great... Aren't they?
March 10, 2008 5:53:29 PM

To sum up, for budgetary reasons, you can go with DDR2667, for performance reasons and so you dont have to mix and match. Buying 800 would mean an upgrade to a cpu with 400 fsb would leave you with just the 2 new sticks running efficiently, and you'd be in the same boat with only 2 GB anyways.

Vista will use up 4 gb of ram if you run virtual machines, folding@home like processes, video/audio encoding, regularly running file compression (a couple of documents in a zip file does not count) or any other number of things. 2 GB is great for normal computing and gaming in vista. Vista Ultimate 64 bit SP1 with a couple of JavaServlets for work running on a q6600@3.2 and 2x2gb of ram idles with 2307 MB in use. When running full bore and other users hitting it I peak at 3500 MB used.
March 10, 2008 7:44:41 PM

http://www.directron.com/fsbguide.html

Hello All,

In this article, Mr. Penrod states:
"Generally you want to keep the system clock of your memory matching with the root clock of your memory or one step above. So the system clock on a 800MHz FSB P4 is 200 (quad pumped) so that matches DDR2 400 (essentially 200 unimproved) or is good with 1 step up DDR2 533MHz (essentially 266 unimproved). Note however that if you only had a 800MHz FSB processor then DDR2 667 really probably isn't going to help much. Once you pass the 1 step above mark on the memory you have diminishing returns unless you can get to double (DDR2 800MHz)."

Does that mean if you have a 1066MHz FSB, you can really benefit with 1066 memory? (2 x 533)

Joe
March 10, 2008 8:26:32 PM

sleeperjoe said:
http://www.directron.com/fsbguide.html

Hello All,

In this article, Mr. Penrod states:
"Generally you want to keep the system clock of your memory matching with the root clock of your memory or one step above. So the system clock on a 800MHz FSB P4 is 200 (quad pumped) so that matches DDR2 400 (essentially 200 unimproved) or is good with 1 step up DDR2 533MHz (essentially 266 unimproved). Note however that if you only had a 800MHz FSB processor then DDR2 667 really probably isn't going to help much. Once you pass the 1 step above mark on the memory you have diminishing returns unless you can get to double (DDR2 800MHz)."

Does that mean if you have a 1066MHz FSB, you can really benefit with 1066 memory? (2 x 533)

Joe


Front side bus really makes this all confusing. Its really the system bus X 4. I don't really care what they say about it. I have run enough of my own tests to reassure myself that with system bus of 266 (FSB 1066), I get better results from running my ram at DDR2 800 spec (400 MHz) then I do from running my ram at DDR2 533 spec (266 MHz).

March 11, 2008 1:41:00 AM

With the price of 2x2GB so low I'd just recommend getting one of those kits @ PC6400. For about $100 you can get 4GB *and* 800MHz capability.

-mcg
March 11, 2008 2:39:37 AM

As an example for 1:1 memory speed to fsb - Q6600 at 1066 = 533 memory, 1333 = 667 memory, and 1600=800 memory. the match to an intel 1600 fsb is ddr2 800 in speed because it runs at a base of 400 MHz. If you want to maintain the stock 2.4 GHz and run 1:1 on your memory to FSB, set your multiplier down to 6, and FSB up to 400. This removes the speedstep function because it can't go any lower, but you'll sit at 2.4 GHz all day - stock speed= safe and full effective use of memory.

The effective number 800 in ddr 2 800 - is that it is running at 400 MHz but can take twice the number of bits at the same time as the previous generation DDR. (i dont know what changes in DDR3, but i imagine its an additional step up in the number of bits transferred at the same time to throttle back the MHz)

This is not to say going faster would not be effective and fast, just don't want any confusion.
March 11, 2008 2:57:21 AM

rockbyter said:
As an example for 1:1 memory speed to fsb - Q6600 at 1066 = 533 memory, 1333 = 667 memory, and 1600=800 memory. the match to an intel 1600 fsb is ddr2 800 in speed because it runs at a base of 400 MHz. If you want to maintain the stock 2.4 GHz and run 1:1 on your memory to FSB, set your multiplier down to 6, and FSB up to 400. This removes the speedstep function because it can't go any lower, but you'll sit at 2.4 GHz all day - stock speed= safe and full effective use of memory.

The effective number 800 in ddr 2 800 - is that it is running at 400 MHz but can take twice the number of bits at the same time as the previous generation DDR. (i dont know what changes in DDR3, but i imagine its an additional step up in the number of bits transferred at the same time to throttle back the MHz)

This is not to say going faster would not be effective and fast, just don't want any confusion.


Reading the original post, did you catch that this is an HP... not doing any OCing. He even says..."Considering NO OVERCLOCKS!". :hello: 

March 11, 2008 5:08:49 AM

It was purely informational, later posts by others were a bit wishy washy
!