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Q6600 and RAM speed confusion...

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August 1, 2007 8:39:31 PM

Yea I know there's another post recently, but it doesn't answer my question.

No overclocking. Going to get a MSI-P35(DDR2) and 8800GTX.

I know the Q6600 is rated at 1066. Does that mean anything less is going to slow the system down?

That other post talks about getting DDR2-800. What about DDR2-667? Mwave is bundling 4GB of their own brand DDR2-667 for 166us.

For about that price I can get 2GB of ballistix 1066. Or for around a 115 (-35 mail in rebate, I hate rebates) I can get 2GB ballistix DDR2-800.

So with the wife annoyed that I've just bought a 360 elite and am looking at dropping another 1200 for PC stuff, I'm trying to figure out which way to go

2gb of 1066, 2GB of 800 or 4GB of 667?

Keep it simple guys :)  My brain hurts today.
August 2, 2007 12:52:00 AM

The Q6600 runs at 266 (266x4=1066) mhz FSB. All you have to do is look at the current number of the memory, and divide that in two to get the correct default FSB of that memory. For example, DDR2 533 operates at 266 mhz FSB, DDR2 667 operates at 333 FSB, and DDR2 800 ram will operate at 400 mhz FSB, etc....

Basically, for best operation, you would want your memory to be at the same FSB speed of your cpu, or faster, in this fashion. Although having faster ram could be a waste of money unless you intend on compatibility for the future cpu's, or for overclocking.

My recommendation....if you are not overclocking, get the 4 gb of 667. Having that much ram is more futureproof than the other 2 options.
August 2, 2007 2:12:28 PM

Groveling_Wyrm said:
The Q6600 runs at 266 (266x4=1066) mhz FSB. All you have to do is look at the current number of the memory, and divide that in two to get the correct default FSB of that memory. For example, DDR2 533 operates at 266 mhz FSB, DDR2 667 operates at 333 FSB, and DDR2 800 ram will operate at 400 mhz FSB, etc....


Why do you divide the cpu by 4? Is it because there are 4 cores? If that's the case, then would a C2D be divided by 2 - making a C2D 1066 faster than a C2Q (533 vs 266)?

Sorry if that's a Dum-dum question, but I'm building a system similar to this.

TIA
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August 3, 2007 4:37:44 AM

No, the reason is not because of the four cores. It is related to the speed of the Front Side Bus, or FSB.

The Core 2 Duo or Core 2 Quad CPU is Quad Data Rate, or QDR, or basically 4 x the FSB. The memory is Double Data Rate, or DDR, thus 2 x the FSB.
August 3, 2007 9:32:07 AM

Yep. so a Q6600 with a FSB of 1066 will be running a 266 FSB.

PC2-4200 aka DDR2 533 runs 533mhz effectivly but is actually running 266mhz.

Those 2 memory's are best compatible. Of coarse you can simply buy better memory and lower the speed. Good for overclocking, buying better memory and underclocking it would also allow you to get lower latencies.
August 3, 2007 11:21:00 AM

If your not overclocking then 4 GB of 533MHz ram is fine, that means you'll be running your CPU at stock and ram at 533MHz. Basicly your CPU and Ram are running a 1:1 ratio CPU & ram are running at the same speed to one another.
August 5, 2007 6:19:56 PM

So why do people who don't overclock buy 1066 ram for these cpus?
August 6, 2007 8:17:50 AM

stromm said:
So why do people who don't overclock buy 1066 ram for these cpus?



They don't know any better.
August 6, 2007 2:38:22 PM

Hi, I'm having trouble with a similar issue, thought it best to tag it on here!

I've just upgraded to a Q6600, Abit Quad GT, 2x2GB Patriot 6400 800Mhz 5-5-5-12 DIMMs and a 8800GTX. I started getting random BSOD and after some troubleshooting it appears to be memory related. I ran Memtest86 with both DIMMs in and got over 20,000 errors after about 30mins! I then ran it for 2 hours with just one DIMM and only got 512 errors. I ran it again for a much shorter period with only the other DIMM in and got a small number of errors.

The BIOS is up to date and all settings are stock. The RAM is at 408Mhz(816) (2:3). Someone on another forum suggested trying the ram at 266Mhz(533) and for the first time I managed to run 3dmark06 successfully. I haven't had a chance to try memtest 86 on the RAM at 533 but will try tonight.

My questions are, should memtest 86 return NO errors or are some normal (if so roughly how many after a couple of hours?). Do you think the memory is faulty if the memtest results after lowering the speed are much better and should I return it as faulty? I don't want to go for weeks with no RAM and I'm wondering if there's really any point assuming the system will run stable at 533.

Any help/input much appreciated!
August 7, 2007 3:29:59 AM

Mr_BABaracus said:
Hi, I'm having trouble with a similar issue, thought it best to tag it on here!

I've just upgraded to a Q6600, Abit Quad GT, 2x2GB Patriot 6400 800Mhz 5-5-5-12 DIMMs and a 8800GTX. I started getting random BSOD and after some troubleshooting it appears to be memory related. I ran Memtest86 with both DIMMs in and got over 20,000 errors after about 30mins! I then ran it for 2 hours with just one DIMM and only got 512 errors. I ran it again for a much shorter period with only the other DIMM in and got a small number of errors.

The BIOS is up to date and all settings are stock. The RAM is at 408Mhz(816) (2:3). Someone on another forum suggested trying the ram at 266Mhz(533) and for the first time I managed to run 3dmark06 successfully. I haven't had a chance to try memtest 86 on the RAM at 533 but will try tonight.

My questions are, should memtest 86 return NO errors or are some normal (if so roughly how many after a couple of hours?). Do you think the memory is faulty if the memtest results after lowering the speed are much better and should I return it as faulty? I don't want to go for weeks with no RAM and I'm wondering if there's really any point assuming the system will run stable at 533.

Any help/input much appreciated!


Sometimes when switching out other ram for the same can cause you problems as I have learned. I had to rma my ram that I had for only two months that went bad, so when I got the new replacement ram back I got tons of errors right away. Someone told me that whenever you put new or old ram in you have to reset your Cmos.

I know some of your guys are saying BS to that but when I was reading a ram review even the authur reset Cmos everytime he changed brands of ram in & out. It seems that resetting the Cmos took my PC from error producing and stability problems to problem free operation, it really worked! Even if you didn't change your ram out try it anyways.
August 7, 2007 9:24:12 AM

This is the first and only RAM that has been in the new MB. Also I have reset the CMOS AND flashed the BIOS since I bought it, all with the same issues. Last night I changed the mem to 667Mhz and ran memtest86 overnight and it passed 3 times with both 2GB DIMMs in with no errors. I'm wondering if the extra 16MHz it was running over the 800 is causing the problem, but I would have thought there would be a much bigger tolerence for errors/overclocking. I was also wondering if maybe increasing the voltage on the RAM slightly might stop the errors.
August 8, 2007 5:08:12 AM

Mr_BABaracus said:
This is the first and only RAM that has been in the new MB. Also I have reset the CMOS AND flashed the BIOS since I bought it, all with the same issues. Last night I changed the mem to 667Mhz and ran memtest86 overnight and it passed 3 times with both 2GB DIMMs in with no errors. I'm wondering if the extra 16MHz it was running over the 800 is causing the problem, but I would have thought there would be a much bigger tolerence for errors/overclocking. I was also wondering if maybe increasing the voltage on the RAM slightly might stop the errors.


What is your current ram rated at? Sometimes running your ram over its rated speed can cause errors. Theres no way to know how far you can OC your ram.
August 8, 2007 8:56:35 AM

Mr_BABaracus said:
This is the first and only RAM that has been in the new MB. Also I have reset the CMOS AND flashed the BIOS since I bought it, all with the same issues. Last night I changed the mem to 667Mhz and ran memtest86 overnight and it passed 3 times with both 2GB DIMMs in with no errors. I'm wondering if the extra 16MHz it was running over the 800 is causing the problem, but I would have thought there would be a much bigger tolerence for errors/overclocking. I was also wondering if maybe increasing the voltage on the RAM slightly might stop the errors.



I would recommend increasing your voltage by .1 to .2 volts. Anything past that, I would not recommend so quickly. I would think it is your voltage that is holding you back.

Let us know what results you get!
August 8, 2007 10:10:28 AM

I too am confused.
If I understand this correctly, I would only need 533MHz RAM to use with a Q6600 that has a 1066MHz front side bus and not 1066MHz to get the best performance.
August 8, 2007 10:52:35 AM


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a b } Memory
August 8, 2007 12:32:15 PM

mitzoff said:
I too am confused.
If I understand this correctly, I would only need 533MHz RAM to use with a Q6600 that has a 1066MHz front side bus and not 1066MHz to get the best performance.


DDR2-533 is the same speed as FSB1066. Because the memory is Double data rate and the CPU FSB is Quad, all companies apply dual-channel memory mode for their performance motherboards. 2x2=4, really.

For reasons that go beyond common logic, the newest chipsets seem to like overstuffing the memory side with DDR2-800 for best performance. But DDR2-533 will work OK with FSB1066 processors.

DDR2-533 won't work at all on the latest P35 chipset boards though, because Intel didn't approve those for use with anything less than DDR2-667. The ratio is there, and DDR2-667 or faster RAM can be manually set to DDR2-533 speed. The problem is that these boards detect DDR2-533 as being "out of range" of the supported speeds. I expect a few motherboard companies may have introduced new BIOS to fix that issue, but I'd play it safe and get at least DDR2-667.
August 8, 2007 12:45:36 PM

Ok thanks.
August 8, 2007 5:15:54 PM

Brings to question doesnt it, why this DDR3 much higher clocks are around, I guess they want us to run it at like 1:2.
a b } Memory
August 8, 2007 6:27:29 PM

Actually, Intel doesn't mind at all if you run 1:2, and memory sellers will love you!
August 8, 2007 8:20:36 PM

I've done some monkeying around with my mem ratio on my Q6600. Going from 900 to 600 increases my mp3 encode time by 2%. FPS in game is nearly the same. Only sandra mem benchies show an appreciable difference, and even then it is only 5%!
August 8, 2007 9:27:31 PM

I'm quite sure I've seen several sites with benchmarks showing a noticeable increase in performance between DDR2-800 and DDR2-1066 with the Q6600. I'll look about later.
August 9, 2007 8:12:13 AM

Crashman said:
Actually, Intel doesn't mind at all if you run 1:2, and memory sellers will love you!


Thats interesting, so if I run it 1:2 id still get lots of extra performance, unlike some? Nice!
a b } Memory
August 9, 2007 8:38:30 AM

Hatman said:
Thats interesting, so if I run it 1:2 id still get lots of extra performance, unlike some? Nice!


Eh, what's performance got to do with anything? Isn't this all about showmanship?
August 9, 2007 8:44:38 AM

Its ALWAYS to do with performance!
!