E7500, 4ghz on AIR

[zuzullo]

3,4ghz at stock voltage
3,7ghz at stock max voltage: 1,3625v
3,9ghz needs 1,400v
4,0ghz is not stable even at 1,500v

Why and how does others manage it with less voltage?
Can two different E7500 CPUs overclock differently?


Details:
4,0ghz @full load = 59°C (still long way to the 74°C limit)
Prime95 does not give any error during that time. Computer simply reboots!
Bus frequency is 364mhz (which is way lower than on my previous OC, so it is definitely not bounded by the MB)

What is it then?
Any clues?

 

[Mugz]

The less voltage is probably because they're using later models to yours, even though the chip itself is identical, the manufacturing process that made them has been refined and the chip tolerances are tighter, allowing a lower voltage.

My guess is either the chip is still not getting enough power (not likely) or your FSB:RAM ratio has become less than optimal (more likely) or the RAM itself is slightly iffy (most likely). Make sure the RAM speed is at or below its rating, make sure the RAM voltage is correct for that speed, and if possible keep the RAM speed and the FSB at 1:1.

Another thought occurs: is your power supply powerful enough to pull the system? Remember that increasing the CPU voltage increases the draw on the +12V rail in the PSU, so in your case it might be just under/just over (depending on the OC).

How long does Prime95 run before the machine reboots?

Also bear in mind that you might have picked up a 'dud' chip. I had that once with two identical P4 631 3GHz chips, where the one hit 5.2GHz easily, yet when swapped with its twin it wouldn't go higher than 3.7GHz...

 

[jsc]

"Can two different E7500 CPUs overclock differently? "

Yes. One of the less obvious determining factors is the chip's VID. This is the voltage that your chip programs the motherboard to deliver. All the Core2 CPU's have a VID range. If, as I put it, you win the CPU lottery, you will get a chip with a low VID. This gives you more OC headroom before you reach Intel's maximum recommended voltage, which for a 45 nm CPU is 1.3625 volts.

Here's part of the Intel spec sheet for the E7500
http://processorfinder.intel.com/details.aspx?sSpec=SLB9Z
Notice that the VID ranges from .85 volts to 1.3625 volts.

 

[Mulder19]

I found that keeping my bus low allowed me to achieve a lower voltage OC. Interesting that you say you lowered your bus prior to this clock. I would have thought that your bus speed could have have been the problem. I would try maxing out the multiplier first then nudging up the FSB. Although, running a voltage of 1.5 to maintain your clock seems very risky.

 

[zuzullo]

The less voltage is probably because they're using later models to yours, even though the chip itself is identical, the manufacturing process that made them has been refined and the chip tolerances are tighter, allowing a lower voltage.

Hummm, I thought that this would be controlled by the Stepping. Mine is RO and the only one produced so far by Intel.

My guess is either the chip is still not getting enough power (not likely) or your FSB:RAM ratio has become less than optimal (more likely) or the RAM itself is slightly iffy (most likely). Make sure the RAM speed is at or below its rating, make sure the RAM voltage is correct for that speed, and if possible keep the RAM speed and the FSB at 1:1.

The RAM shouldn’t be a problem because I have been running this RAM on 2.1v for 3 years at 390mhz+ (which is within the manufacture limits) and now its running only at +-360mhz. (always 1:1ratio)
The same way that I think I don’t need to add voltage to the FSB because it use to be in auto in the previous OC.

Another thought occurs: is your power supply powerful enough to pull the system? Remember that increasing the CPU voltage increases the draw on the +12V rail in the PSU, so in your case it might be just under/just over (depending on the OC).

I think that this could be a problem maybe. How can I test that? I tried to disconnect all unnecessary hardware and run the system again with only few memory dimm, one hard drive and graphics card…. but it crashed the same way. Is this a prove that my 550W PSU is not powerful enough?

How long does Prime95 run before the machine reboots?

Prime95 runs for about 10min and then the computer simply reboots. (no error message on Prime95)

Current stable settings are:
E7500 @3.96Ghz Vcore:1,46v
BUS: 360mhz (MB can do 390mhz+ tested by me on another cpu)
RAM: 2.1v, 360mhz, 1:1 ratio, (all within manufacture limits)
FSB: auto (it has been in [auto] in a previous higher OC on another cpu)
MCH: 1,60v
PCI-X: 100mhz

Any Idea how to pass this barrier?

 

[overshocked]

Raise the Nbridge voltage.

 

[zuzullo]

Raise the Nbridge voltage.

It is already set at 1,60v. Very close to the limit 1,65v of my Asus P5W DH Deluxe
I tried that and raised the BUS by 4mhz and it crashed! So its either not about the NBridge or I would need a voltage bigger then 1,65v!!!

Do you think that this represents the limit of the this E7500 chip or MB?

 

[zuzullo]

Hold up, list me your specs with good details
and all your known voltages, multipler settings
dram settings, bus etc..as much as u can
also which program you monitor your temps by
sorry i made a mistake above..
(core temp) the TJ MAX is 100C for your e7500, if the program your using is with the wrong TJ MAX this could lead into inaccurate temp reading. make sure u change it

the 74C you said is from the intel website i know..if you click on it, it'll say
"Thermal Specification: The thermal specification shown is the maximum case temperature at the maximum Thermal Design Power (TDP) value for that processor. It is measured at the geometric center on the topside of the processor integrated heat spreader. For processors without integrated heat spreaders such as mobile processors, the thermal specification is referred to as the junction temperature (Tj). The maximum junction temperature is defined by an activation of the processor Intel® Thermal Monitor. The Intel Thermal Monitor’s automatic mode is used to indicate that the maximum TJ has been reached."

Thanks for quick replay,

I dont seem to have problems with temperature. I checked on this list of Tj max and I confirmed its 100°C for all E7000 chips. That was the pre-definition of RealTemp v3.0 and its still reading 59ºC as Max temp under full load (room temperature is 22ºC)

Have a look at my current stable settings:
E7500 @3.96Ghz, Vcore:1.46v, and I found this value as well “+12v”=12.51v
BUS: 360mhz (although I know that my MB can do 390mhz+ tested by me on another cpu, E6300)
RAM: 2.1v, 360mhz, 1:1 ratio, (all within manufacture limits, RAM has also been running before at 390mhz+ with no prob.)
FSB: auto (it has been in [auto] in a previous higher OC on another cpu. I tried 1,30v but the reaction was the same)
MCH: 1,60v (have tried the max 1,65 of the MB and didnt help)
PCI-X and PCI are locked at 100 and 33 respectively.

What is weird is that even when I lower the multiplier to 10x, I can only reach 370mhz under the same settings. Shouldn’t it be able to accept much more bus frequency at lower multiplier? Even feeding more power into MCH=1,65v and FSB=1,30v didn’t help to pass 370mhz.

Do you think this is the limits, I am running out of options!

 

[zuzullo]

okay so heat isnt the problem , now thats outta the question..
normally changing the multiplier should do it, umm..

is your ram latencies on auto or manual?
what is your power supply..
list me all your hardware too\

edit: im beginning to think its your ram thats the problem.

Ram latencies are on [auto]. Like this, they remain always lower than their limits, as you can see on the picture above! Should I put them on [manual] using the values listed on the last column of the CPUz?

RAM = 2x1Gb Gskill 6400 cl4 2.1v, in dual-channel
PSU = LC Power 550w Could that be a problem?
MB = P5W DH Deluxe, latest bios2901 (people have reached 420mhz of bus speed on this MB)

Thanks in advance!

 

[zuzullo]

set your ram latencies to the default i believe its 5-5-5-15..
list video card..other stuff (sound card)..etc
i wanna calculate if you have enough power
what is your VID for your cpu, check in cpuz

Isnt the default latencies the ones listed on the right column of CPUz, the EPP #1 ?
VID is 1.3625v but as you can see it is now at 1.4625v (0,1v above limit)

The rest of the configuration is.
HDD = 2x western digital velociraptor on Raid 0 Matrix
HDD = 1x Maxtor 320gb
VGA = Nvidia GeFoce 7600GS 256mb passive cooling (I am not a gamer, I am a photographer that needs to work on LightRoom faster)
DVD = 1 plextor
Sound = 1 creative 5.1 player (a cheap one)
TV = Leadtek 2000xp

Is that ok? Anyway, as I said I have tried to disconnect most of them and it still didnt improve my OC not even 4mhz!!!

Please share you calculations!

 

[Guest]

Isnt the default latencies the ones listed on the right column of CPUz, the EPP #1 ?
VID is 1.3625v but as you can see it is now at 1.4625v (0,1v above limit)

The rest of the configuration is.
HDD = 2x western digital velociraptor on Raid 0 Matrix
HDD = 1x Maxtor 320gb
VGA = Nvidia GeFoce 7600GS 256mb passive cooling (I am not a gamer, I am a photographer that needs to work on LightRoom faster)
DVD = 1 plextor
Sound = 1 creative 5.1 player (a cheap one)
TV = Leadtek 2000xp

Is that ok? Anyway, as I said I have tried to disconnect most of them and it still didnt improve my OC not even 4mhz!!!

Please share you calculations!

ive got the same chip and get 4ghz at 1.4v, the max ive used is 1.42v 525fsb x 8. it will go to 3.8ghz all on auto at 1.31v but top get 3.9 the voltage needs to be at least 1.39v.
i use the same settings to get 4ghz at 366x11, 400x10, 466x9. 1.4v cpu, fsb 1.3v-1.35v, ich 1.55v-1.6v, mch and everything else on auto,never lets me down. i cant get it to boot at all between 410-425fsb with any ratio and any settings,my systems a no go between that 15fsb. get a p45 mobo, you'll have loadsa fun with ya e7500, 525fsb x 8 is awesome.
i'd be worried going uo near 1.47v,stick with 3.9ghz, the 100mhz difference is very small and not worth straining ya hardware for. good luck.