Need Help (Again)

[HomZ]

After giving up trying to get my last setup stable i replaced the board and memory with some newer kit

Ive bought a Asus p5kc and Corsair Dominator 8500 (1066 memory)

Now given the board says it supports 1066 memory and fsb i thought with my chip being 1066 everything would run nicely together, not the case

When i booted the machine and went into the bios it has set my memory to 800mhz by default, if i set it to 1066 it doesnt post after i save and exit the bios, i have set the memory voltage and timmings correctly but still it doesnt post after a reboot or exiting the bios, on a few occasions i set the mem voltage to 2.2 and it would post at 1064 ? but wouldnt let me do an install.

Currently running at 1066fsb and the memory at 800mhz its working fine although why cant i get 1066 out of it? thats the whole reason i bought it

Not intrested in overclocking just yet, although when i do get it stable i was planning on running the chip at the 3gig mark

Thanks

 

[semi-pro waster]

What divider are you running on the Ram? Note that the following is partly as a joke because you will almost certainly have some sort of divider on the system to get it to boot like that but there is a bit of a point behind it as well.

Going back to basics here, Core2Duo/Quads have a quad-pumped FSB in effect so to get a speed of 1066mhz on the FSB you need 267mhz from the Ram (i.e. PC4200 speeds) if you were booting at 1066mhz on the Ram you would be running at 4x533mhz giving you an FSB of 2132mhz and assuming a 9x multiplier a potential clock speed of ~5ghz. There is a reason it won't boot and run like that.

As it is if it is defaulting to 800mhz you have the Ram running at PC6400 speeds and again assuming a 9x multiplier you could be booting at 3.6ghz unless you have unlinked the Ram from the FSB and I'm afraid you can't do that with the Intel chipset of your motherboard. So we come back to the divider and checking that setting - there is plenty of more detailed advice about the P35 chipset and the best ratios etc in the motherboard or overclocking sub-forums.

 

[HomZ]

I wasnt sure if the fsb and mem did have to run in sync, i assumed a 1066 chip would run with 1066 memory

When i first turned the system on everything in the bios was set to auto, inc the memory, it was only when the machine was posting i saw it say 800mhz dual channel mode

According to cpuz im running a 1:1 divider although i cant see where it actually gives me the numbers in the bios, if i set my cpu fsb to 266 then the ram is at 533 (which is right) 1:1 right ?

I just assumed it would run all together at 1066, this whole new gen of ddr2 and core 2 duos has gone right over my head so im still trying to understand it all properly,

Ive been reading a few guides and im starting to get my head around it, ive set my cpu fsb to 350 with a multi of 9 so thats 3.2ghz ish which it seems to be happy with, in cpuz it now says my resulting fsb is 1400, where do we get this figure from ?

And if 1066 chips require 533 memory and 1333 chips require 667 (to run at stock) why do we have 1066mhz memory, i understand that overclocking will play a big part in some peoples choices, taking my setup for example has 1066 mem been a bad choice ? im never going to get anywhere near that am i without having a crazy fsb overclock

Sorry if i havent quite worded any of this right or if i have come across as a total noob

Could someone give me an example of how 1066 mem would run at 1066 ? will help me understand it more i think

Ill take a look over in those sections you told me about

Thanks

 

[davethe11]

What cpu is it homz? Also, i've just read (very briefly) up on your ram as I was curious that it is 1066 mhz ram given that it is called 8500 (which would usually indicate that it is 8500 mhz ram, but im not familiar with corsair naming conventions so may be wrong). I read that some folk with this ram set the ram voltage (vdimm) to 2.1v to get their system stable, can you tell us what ram voltage you set?

[edit] by the way, intel processors have what is called a 'quad pumped' technology that effectively quadruples the front side bus, this is why cpuz is reporting a fsb of 1400 (quad pumped 350 mhz, or 4x350 = 1400)

 

[semi-pro waster]

Could someone give me an example of how 1066 mem would run at 1066 ? will help me understand it more i think

Ill take a look over in those sections you told me about

Thanks

davethe11 has explained why your FSB is at 1400 there. If you wanted your Ram to actually run at 1066mhz (533mhz actual speed) then you would need to lower the multiplier on your CPU (some people do this because it increases the memory bandwidth available although there may not be a hugely apparant benefit) so you'd have an FSB speed of 2132mhz (approx) and say you used a 6x multiplier (you can go down from a higher multiplier but not up on these Intels) you'd get that same 3.2ghz you currently get from 9x355mhz.

Hopefully that helps a little.

davethe11, it is PC8500 because of the peak transfer possible which is approx 8.5gb/s from the rated speed of 533mhz (actual), that is how all speeds of DDR2 are named essentially. Wikipedia has a bit more of an explanation here.

 

[HomZ]

Hi yah Dave, ive set the memory to 2.1v which it says to do on the sticks themselves,

The 1400 make's sence now, i think ive been confusing myself with the numbers

As mentioned earlier i was running a 1:1 divider so that was never going to boot i realise that now, im currently running 360fsb with a multi of 9 which gives me just over 3.2 which im going to leave running orphos, its been running over 2 hrs now without a problem, thats running a 1:1 divider still which seems to be faster when using 3dmark, when i had the divider at 2:3 i think it was ? i got close to 1066 so i understand how it works now but ill leave it at 1:1, it seems my chip will do 3.2 easy enough.

Would setting my fsb to 400 (which would run my mem at 800 (1:1) ) and using a multi of 6 to get me 2.4 work ? would this board run at 400, would i seriously have to start bumpin the voltages to achieve this ?

If that worked i could then keep uppin the multi to increase the clock speed of the chip right ? do i sound like im understanding it

Thanks for your help guys, very refreshing to find people that dont wana take the mick

 

[davethe11]

davethe11, it is PC8500 because of the peak transfer possible which is approx 8.5gb/s from the rated speed of 533mhz (actual), that is how all speeds of DDR2 are named essentially. Wikipedia has a bit more of an explanation here.

thanks semi-pro, my brain wasnt in gear earlier and ive realised my mistake (been a long day!).

266 mhz fsb x 2 x 2 (ddr2) x 64 bit bus / 8 for bytes = 8500 Mega Bytes per sec

im still adjusting to ddr2 lol my mind is still in the sdr and ddr era



[edit] Homz, 6 x 400 will give you 2.4 ghz, of course this is an underclock from 3.2 ghz. Upping the multi is not the best way to find a good overclock initially, you want small changes in fsb so your cpu overclocks in small steps:

for example, starting with 9 x 360:

increasing the multi to 10 will increase the cpu clock speed by 360 mhz, quite a mighty jump in clock speed when you want to gradually push your cpu looking for a good stable overclock

alternatively, increasing the fsb by, say, 5 will increase the cpu clock speed by 45 mhz (5 fsb x 9 multi) - a smaller overclock but better as you want to gradually overclock. Most people would recommend increasing fsb by only 1 at a time when you are new to overclocking, you will get the feel for whats going on with the numbers, and you can keep an eye on temps closer and with more confidence imho.


Overclocking is about finding two things: what is the highest cpu clock speed you can reach and be stable, and what is the highest memory bandwidth you can achieve and be stable. You can only find one of these at a time: when you want to find your cpu overclock potential, you want to slow down your ram (use dividers here, or some bioses allow you to set the memory bus speed independantly of the cpu fsb) so you know that when your system stops posting/booting/being stable it is because of the cpu. And when you want to find your memories overclocking potential (you may be happy with just a cpu overclock of course), you want to slow down your cpu (usually by lowering the cpu multi) so that when your system stops posting/booting/being stable you know it is because of your memory and not the cpu.

hope this helps

 

[HomZ]

More than happy with just a cpu overclock, A memory overclock wont be happening as the memory is rated to run at 1066 and as im sticking with the 1:1 divider i wont get anywhere near that.

Im not new to overclocking ive done it with the older athlon chips and 64 bit athlons just never delved into the intel chips and with the fsb's being so much higher now and the voltage being a lot lower its like im starting at ground zero again which i dont suppose is a bad thing.

Ive read theres a lot of people running 400x8 = 3200 (1:1 Memory at 800mhz) stable with similar spec to mine so as you said working my way up i have got to this speed and are running orphos as we speak on it, this has been going for an hr and half with no errors, the only thing that is concerning me is the temps, with 2 instances running im hitting 67 degrees with stock cooler, my room is stupidly warm though, may have to order new cooler in the morning so look out for a new thread (just kidding)

I can honestly say i wouldnt push it over 3.2 so if its still running ok by say 9am ill leave it as it is

Thanks again