Prohibited links edited
Markfw900
Anandtech Moderator
Courtesy of Saaya at Xtremesystems.org
Core i7 920 at 4.2ghz Cpu-Z validated:
http://valid.x86-secret.com/show_oc.php?id=440058
(people at XS think this might be a fake screenshot because it uses a 22x multi on an i7 920 model - which is supposed to max at 21x.)
Core i7 920 Priming at 3.8ghz:
http://www.matbe.com/images/bi...ivers/000000078330.png
Core i7 Retail Box pictured:
http://i373.photobucket.com/al...75/gooddog2008/004.jpg
Retail Box Stepping & CPU-z pic:
http://valid.x86-secret.com/show_oc.php?id=440677
Core i7 965 XE running 200mhz base clock on MSI X58:
http://img2.abload.de/img/200cpuzql1z.jpg
Core i7 965 XE at 5.0ghz Cpu-Z validated:
http://valid.x86-secret.com/cache/screenshot/440470.png
http://uneit.com/xpres/wp-cont...08/11/5005-1-thumb.gif
http://uneit.com/xpres/wp-cont...2008/11/5037-thumb.gif
5.4ghz:
http://fugger.netfirms.com/nhm/cpu.JPG
Update:
Nehalem 101
"Hey guys,
thought id post some details so your already prepared for nehalem and how to clock it.
Ill try to post more details here bit by bit as i have the time
Clocks:
Instead of the FSB Nehalem uses a reference clock like AMD, but its at 133Mhz and not 200Mhz.
This reference clock is multiplied to create all clocks inside the CPU:
Bclock x CPU Multiplier = CPU Clock (12-256)
Bclock x QPI Multiplier = QPI Clock (18, 24)
Bclock x Uncore Multiplier = Uncore Clock (10-30)
Uncore clock / Memory Divider = Memory clock
Great Clockspeed Expectations:
222Mhz Bclock screenshot on ln2
200Mhz Bclock stable on air
8GT/s or 4Ghz or below QPI speed, cooling doesnt matter
6Ghz or below screenshot with 1 core on ln2
5.5Ghz or below 3d stable with all 4 cores on ln2
4Ghz or below 3d stable with all 4 cores on air
2100Mhz or below tri channel stable on air
Overclocking:
If you have an XE cpu its all easy, you just change the CPU Multiplier to increase the CPU Clockspeed, thats it...
If you dont have cpu multiplier access, then things get a bit tricky
You need to push up the Bclock, which is related to all other clocks though... so when you increase the Bclock you overclock every part of the processor.
QPI, Uncore and the memory controller/memory.
Crime Scene Investiagtion errr i mean QPI:
You dont really want to overclock QPI though...
Just like HyperTransport QPI is way overpowered for a Desktop system and only really useful for Servers, and you wont see any notable improvements from clocking the QPI bus higher. So while overclocking it wont really give you any benefits, thats what you have to do if you want to overclock your cpu via the Bclock.
It usually maxes out at around 8GT/s, which is around 4Ghz, and as you have seen from the details above, there are only 2 multipliers you can select unfortunately, which will limit your overclocks on Bclock for the 920 and 940 parts. The lowest multiplier you can select is 18. If you do the maths, that means you will be limited to a Bclock of 222. That is IF you processor and board can run 4Ghz QPI... some cant run that high...
Can I get an Uncore do you want more?
Now about Uncore, Uncore is the L3 cache and memory controller, and its powered not by Vcore, but by VTT. I guess Intel couldnt decide what to call this part of the cpu and then went for Uncore which pretty much means its not the core... not very creative, but it gets the job done
Im sure youve seen many if not all mainboard manufacturers using one or two or even 4 phases of a CPU PWM to power the VTT. While on Core2 VTT consumed around 10-15W and you could use a basic PWM to feed it, it now needs double that power, around 30W, and when your overclocking, even more, naturally...
3-some Memories: mhhh good times, good times
The memory controller inside the "Uncore" needs to run at two times the memory BUS speed or more. So for DDR3 1066 (533Mhz memory clock) you need the Uncore to run at 2133Mhz or higher. There are different memory dividers though to clock the memory lower than half the speed of the memory controller/Uncore. According to Intel all CPUs will have all memory dividers unlocked, and will have all the Uncore ratios unlocked, so you guys will be able to run even the highest memory speeds, even with the slowest Nehalem cpus.
Well the highest means an uncore speed of 30x133=4000Mhz /2=2000Mhz
If you want memory speeds beyond DDR3 2000 (1ghz memory clock) you will have to overclock the reference clock. The highest theoretical memory clock with 222Mhz as the highest Bclock is 30x200=6000Mhz /2=3000Mhz.
So DDR3 3000 (1500Mhz memory clock) so this shouldnt be a limit
Memory kits above 2ghz, like the corsair 2133 Kit or the rumored DDR3 2400 kits we all heard of wont be possible without overclocking the cpu though! keep that in mind... then again so far it seems memory can clock higher on x48 than nehalem, but nehalems 3some goodness kills those huge clocks of x48 in every benchmark...
Apprently it seems to be quite useful as well to overclock the Uncore even if you dont want to run huge memory clocks. Remember it contains the L3 cache, so overclocking it will reduce L3 cache latencies and we all know that the higher the memory controller is clocked, the more efficient it works and the higher the bandwidth, even if the memory is still running at stock.
Here are some recommended settings for you i got a from a friend at intel.
if your reading this, cheers man
How to find max Bclock:
Bclock 133Mhz
CPU Multiplier 12x/14x
Uncore Multiplier 2x memory speed or higher
QPI Multiplier 18x
High memory Divider for low memory clock
Vcore 1.25v
VTT 1.45v
Vdimm 1.65v
push up the Bclock and increase VTT and QPI volts to get higher.
Max 100% safe VTT seems to be 1.65v
How to find max Mem clock:
Bclock 133Mhz
CPU Multiplier 12x/14x
Uncore Multiplier 2x memory speed or higher
QPI Multiplier 18x
Chose Memory Divider and Timings
Vcore 1.25v
VTT 1.45v
Vdimm 1.65v
push up the Bclock and increase VTT and Vdimm to get higher.
more vdimm and vtt than 1.65v at your own risk
1.8vdimm should be 100% safe though
How to find max CPU Clocks on i7-965:
Bclock 133Mhz or lower
CPU Multiplier 24x
Uncore Multiplier 2x memory speed or higher
QPI Multiplier 18x
High Memory Divider for low memory clock
Vcore 1.25v
VTT 1.45v
Vdimm 1.65v
reduce Bclock, then increase the cpu multipliers step by step.
push up vcore to get higher clocks stable
How to find max CPU Clocks on i7-940/i7-920:
max Bclock
CPU Multiplier 15x
Uncore Multiplier 2x memory speed or higher
QPI Multiplier 18x
High Memory Divider for low memory clock
Vcore 1.25v
VTT 1.45v
Vdimm 1.65v
increase CPU multipliers step by step, push up vcore to get higher clocks stable. if you cant get a multiplier stable, reduce Bclock until your stable.
Max bclock for high multis is slightly lower than for low multis.
The return of the Turbo-Button?
The max turbo multipliers are stored in seperate registers from the "normal" max allowed cpu multipliers, and they can not be changed (unless you hack the cpu ) The turbo multipliers can not be forced to stay on all the time... at least not directly... you can fool the cpu into believing all the conditions that are necessary to run turbo mode are there, even if they are not
the highest boot multiplier is the highest "normal" multiplier...
for the i7-965 it works like this:
IF turbo is disabled
OR vcore is unstable
OR current is too high
OR Tdp is too high:
4 cores will run at 24x133=3200Mhz
3 cores will run at 24x133=3200Mhz
2 cores will run at 24x133=3200Mhz
1 cores will run at 24x133=3200Mhz
IF Turbo is enabled
AND vcore is stable
AND current is ok
AND the TDP is below the limit
4 cores will run at 26x133=3450Mhz
3 cores will run at 26x133=3450Mhz
2 cores will run at 26x133=3450Mhz
1 core will run at 27x133=3600Mhz
for the i7-940 it works like this:
IF turbo is disabled
OR vcore is unstable
OR current is too high
OR Tdp is too high:
4 cores will run at 22x133=2933Mhz
3 cores will run at 22x133=2933Mhz
2 cores will run at 22x133=2933Mhz
1 cores will run at 22x133=2933Mhz
IF Turbo is enabled
AND vcore is stable
AND current is ok
AND the TDP is below the limit
4 cores will run at 22x133=2933Mhz
3 cores will run at 22x133=2933Mhz
2 cores will run at 22x133=2933Mhz
1 core will run at 23x133=3050Mhz
so you see, turbo is really not that useful for most of the cpus, its only useful for the 965, where it basically auto overclocks the cpu... so basically the Core i7 lineup looks like this:
920 2800Mhz BUT if vcore is unstable, current is too high, or temps are too high, it will run slower.
940 3050Mhz BUT if vcore is unstable, current is too high, or temps are too high, it will run slower.
965 3600Mhz BUT if vcore is unstable, current is too high, or temps are too high, it will run slower.
What turbo really is, is a more advanced form of throttling the cpus from those clockspeeds down to a SAFE speed that will work even with high temps, fluctuating vcore and high current. instead of advertising a 3600mhz cpu that throtles down to 3400 or less depending on the situation, which would cause a lot of complains, the cpus are rated at 3200mhz and everything else above it is a BONUS, so nobody can complain
This is it or now, ill add more details later on. if you have any questions, just ask "
------------------
Original post:
"Instead of the FSB Nehalem uses a reference clock like AMD, but its at 133Mhz and not 200Mhz. This reference clock is multiplied to create all clocks inside the CPU:
Bclock x CPU Multiplier = CPU Clock (12-256)
Bclock x QPI Multiplier = QPI Clock (18, 24)
Bclock x Uncore Multiplier = Uncore Clock (10-30)
If you have an XE cpu its all easy, you just change the CPU Multiplier to increase the CPU Clockspeed, thats it...
If you dont have cpu multiplier access, then things get a bit tricky
You need to push up the Bclock, which is related to all other clocks though... so when you increase the Bclock you overclock every part of the processor.
QPI, Uncore and the memory controller/memory.
You dont really want to overclock QPI though...
Just like HyperTransport QPI is way overpowered for a Desktop system and only really useful for Servers, and you wont see any notable improvements from clocking the QPI bus higher. So while overclocking it wont really give you any benefits, thats what you have to do if you want to overclock your cpu via the Bclock.
It usually maxes out at around 8GT/s, which is around 4Ghz, and as you have seen from the details above, there are only 2 multipliers you can select unfortunately, which will limit your overclocks on Bclock for the 920 and 940 parts. The lowest multiplier you can select is 18. If you do the maths, that means you will be limited to a Bclock of 222. That is IF you processor can run 4Ghz QPI... some cant run that high...
Now about Uncore, Uncore is the L3 cache and memory controller, and its powered not by Vcore, but by VTT. I guess Intel couldnt decide what to call this part of the cpu and then went for Uncore which pretty much means its not the core... not very creative, but it gets the job done
Im sure why youve seen many if not all mainboard manufacturers using one or two or even 4 phases of a CPU PWM to power the VTT. While on Core2 VTT consumed around 10-15W and you could use a basic PWM to feed it, it now needs double that power, around 30W, and when your overclocking, even more, naturally...
The memory controller inside the "Uncore" needs to run at two times the memory BUS speed or more. So for DDR3 1066 you need the Uncore to run at 2133Mhz or higher. There are different memory dividers though to clock the memory lower than half the speed of the memory controller/Uncore. According to Intel all CPUs will have all memory dividers unlocked, and will have all the Uncore ratios unlocked, so you guys will be able to run even the highest memory speeds, even with the slowest Nehalem cpus.
Apprently this seems to be quite useful as well to overclock the Uncore... remember it contains the L3 cache, so overclocking it is supposed to reduce L3 cache latencies and we all know that the higher the memory controller is clocked, the more efficient it works and the higher the bandwidth, even if the memory is still running at stock."
source:
http://www.xtremesystems.org/f...?p=3379790&postcount=1
Last edited by a moderator:
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