i7 860 5°C-15°C hotter than i5 750 and tougher to OC

[IanM]

I've got a bit of a dilemma re my two CPUs, I bought the 860 because I was having a heck of time trying to stabilise my system while running 8GB RAM at 1800Mhz-2000Mhz. That issue isn't completely solved and the 860 is only a little better as it can run the x12 memory multiplier. I need to decide fairly soon which CPU to keep and which to sell (I can't afford to keep both)

The i7 860

• It seems stable at BCLK 161 and 'auto' multiplier ( 3.38GHz) with C-state enabled. So I think Turbo mode will work like this. Arguably a pretty decent compromise for an everyday/gaming system. However it does seem to run quite a bit hotter, hitting 80°C and requires maybe an extra 0.1V-0.2V compared with the 750.
• I think can get the temps down a bit with voltage tweaks and re seating my cooler (Corsair H50) but I feel there's not much headroom if I want to push the CPU at a later time
• 860 seems less happy with higher BCLK and x10 memory compared with the 750
• It will boot into windows at BCLK 167, but ram is at 2004-2009Mhz and I suspect 8GB will never be stable that high

The i5 750

• 750 can do 3.6GHz-3.8Ghz with no effort on 4GB RAM and I suspect it would crack the 4Ghz barrier if I was willing to volt it high enough. With lower clocks I imagine it will be possible to get c-state working, and stabilise with all 8GB memory installed
• However at anything over 195 BCLK with 10 memory multiplier 4GB is always disabled and unavailable, I've got to the point where I think I would have to use a much lower RAM speed to get proper stability with the 750 / 8GB combination

The memory problem
I don't need to run the RAM at full speed particularly, but having spent the extra cash on it I'd like it to be running at least somewhere near spec. I put a longer description of what happens on a thread in the memory forum: http://www.overclockers.com/forums/showthread.php?t=639992

The questions

• does anyone have tips on how to get more speed from an already hot 860?
• does anyone have an idea of how to get 8GB stable at high BCLK with i5 750?
• I notice that the Lynnfield overclocking guide on this website suggests 1.35V on VTT - is this really safe? I thought that is hugely over spec for these CPUs. I briefly tried 1.36V, but it made no difference anyway.

I'm hoping Asus or Kingston might help with suggested timings or voltage settings, and maybe even a BIOS update will improve the RAM situation. Not holding my breath for this though.

 

[Nhut Pham]

Have you tried running only 2 sticks of ram instead of 4? Many people have run higher VTT values when running more sticks like you are, I mean I've seen numbers up to 1.65V run 24/7, that's not to say I would feel comfortable running that, but some RAM manufacturers have told people to run voltages this high to achieve stability.

It might be easier to run two sticks to see what kind of overclocks you could get, and if you're not using your computer for much encoding or graphics you very likely could do very well with 4GB.

What kind of temps are you getting? Are you enabling hyperthreading? I'm sure if you disable it for the sake of overclocking (I've seen many really have to do this), you probably will achieve a higher overclock.

Perhaps you can do a couple of these things to really know where your chip stands, it might not be as bad a clocker as you think. It's definitely harder to get a stable overclock with 4 sticks of ram, no matter which chip you choose.

 

[Brutal-Force]

Your problem is completely normal for what your experienceing from the i5 and i7.

The i7 860 typically runs 10-15 degrees warmer than the i5. This is caused by the hyperthreading. Turning HT off in bios will show you the difference in temps.

The increased temps make it a little more difficult to over clock the i7. The Xigmatek 1283 is a good budget cooler, but it has a hard time keeping up with the i7. You could try some higher speed fans which may help, but the end result would be if you want higher overclocks from either of the processors, investing in high end air like the Venomous X, Cogage, TRUE or Noctua D-14.

As for which is better, at lower overclocks like what your using, the i7 would be more suited for general computing. If your looking for a higher overclock, the i5 will probably do a better job, but realistically, only about 100-200MHz better, which for real world application is no big deal.

In my experience, with higher ammounts of RAM a higher Vtt/IMC is needed. Not sure exactly why, but it is true. If i take out 4 gigs of RAM it is easier for me to stabilize with a lower Vtt. at 4131MHz, I need 1.41Vtt to stabilize my OC. Without, the number is closer to 1.35.

Hope this helps.

to OCF!

 

[IanM]

Time to follow this up I think as Nhut Pham and Brutal-Force took the time to offer their thoughts

Have you tried running only 2 sticks of ram instead of 4? Many people have run higher VTT values when running more sticks like you are,

Indeed, used memtest v4, run 4GB at a time using 200 x10 & 167 x 12 without issue so I don't think the memory is faulty. I did try some high VTT briefly with 8GB but as far as I could tell it made no difference, was still getting black screen power off/reset with no warning. Like you I'm not too comfortable over volting the IMC too much long periods.

It might be easier to run two sticks to see what kind of overclocks you could get, and if you're not using your computer for much encoding or graphics you very likely could do very well with 4GB.

I played a little with the 750 to see if it would go higher on 4GB, couldn't do any more with it. It might go higher on more core voltage than I was willing to use. Haven't really tried pushing the 860 with 4GB

What kind of temps are you getting? Are you enabling hyperthreading? I'm sure if you disable it for the sake of overclocking (I've seen many really have to do this), you probably will achieve a higher overclock.

Temps are complicated, and it may well be that I do have a thermal problem but not specifically with the CPU core. I have:

• Lian Li PC-A05N
• Corsair H50 with push-pull and two shrouds
• various fans: Noctua, Lian Li and Gentle Typhoon

On the face of it you look at that and say H50 push-pull = lots of cooling headroom. In fact I have seen 17°C idle on the 750 as reported by other users. However: the PC-A05N case is small and unconventional layout with the airflow direction reversed, intake at the back vent from the front. It does have a real tendency to allow the heat to build up over time. I'm waiting for an alternative case top panel with extra vent and fan mount to try and optimise the air flow.

As my H50 is mounted at the front it's venting, drawing hot air from inside the system so it's not optimal for the CPU cooling. That said at 3.8-3.9Ghz the 750 is 75ish°C. The 860 is already 75°-80°C at only 3.4-3.5Ghz, and HT off only drops the load temps a couple of degrees. These temps are OK as far as I know for the CPU core itself, maybe the IMC isn't included in the temperature sensor and it's overheating? Or it could be something else important is overheating and forcing shut down for safety.

I have a new theory now too, the H50 retention bracket appears to stress the motherboard, so I have begun to wonder if there is some thermal expansion occurring that causes a circuit break and reset - I haven't been able to confirm this theory, it's just an idea and maybe completely wrong

Your problem is completely normal for what your experienceing from the i5 and i7.

The i7 860 typically runs 10-15 degrees warmer than the i5. This is caused by the hyperthreading. Turning HT off in bios will show you the difference in temps.

Useful to know, I experimented with disabling Hyper-Threading and noticed a few of things:

• The temperature difference was only a few °C on my system, though that difference may become wider more critical at higher clocks
• Hyper-Threading reduces the GFlops throughput of IntelBurnTest by 4% (not really a suprise)
• C1E power save mode plays havoc with the performance while overclocking - performance falls away a lot with each loop of IBT: 50GFlops -> 45GFlops -> 40GFlops -> 37 GFlops (looks like thermal throttling, but isn't)

You could try some higher speed fans which may help, but the end result would be if you want higher overclocks from either of the processors, investing in high end air like the Venomous X, Cogage, TRUE or Noctua D-14

See above, I have an H50, a bunch of Noctua fans and 3x Gentle Typhoons for 1850rpm each. Interesting side note: GTs are more effective at cooling the H50 radiator than the Noctua's, but GTs are whinier and much less pleasant, even when down volted In my config 1850rpm actually increases the idle temps compared with 1000rpm down volted GTs!

As for which is better, at lower overclocks like what your using, the i7 would be more suited for general computing. If your looking for a higher overclock, the i5 will probably do a better job, but realistically, only about 100-200MHz better, which for real world application is no big deal.

I did some comparison using IntelBurnTest and turned off HT on the 860. At close or the same clocks the power consumption and GFlops throughput of both CPUs is basically the same. Shouldn't be surprising at all, but I honestly didn't expect them to be so close, damn near identical in fact!

I need to prove it with longer tests, but using auto multiplier, Turbo mode and C-state enabled I was able to get:

• i5 750 : 180 x auto (3780MHz on 4 cores) 8W idle, 190W load. 54.4 GFlops IntelBurnTest
• i5 750 : 160 x auto (3360MHz on 4 cores) 7W idle, 155W load. 49.3 GFlops IntelBurnTest

After disabling C-state ansd using fixed multiplier:

• i5 750 : 190 x 21 (3990MHz) 58.4 GFlops

Overall I'm seriously impressed with how easy it was to do this, and the fact that it doesn't need any heavy over volting to do it!

As for the i7 860, well I messed around and lost the good settings as 160 BCLK is now resetting the machine after a few seconds or minutes of IBT. Now I'm back to 150-155 BCLK to make it stable with C-state and Turbo mode, but the performance in GFlops has dropped too so something is definitely awry (it's actually quicker at 150 BCLK)

I also noticed with one experiment to lower VTT that although the system was stable, actual performance was 30%-40% lower than with the 'correct' VTT. So things are more complicated than I realised - stable high Ghz is not necessarily performing better than stable lower clocks.

to OCF!

Thanks!

Question about Hyper-Threading
is it really worth having for typical home desktop use? I know it's mostly useless for gaming, but does it really boost desktop applications and multitasking in a way that is noticable for home users?

 

[MIAHALLEN]

Question about Hyper-Threading
is it really worth having for typical home desktop use? I know it's mostly useless for gaming, but does it really boost desktop applications and multitasking in a way that is noticable for home users?

All depends on your definition of "home user". Surfing and posting on forums, no....encoding BluRay movies...YES!!!

Overall, I personnally think you're a bit too concerned with high memory speeds. If you're concered about the "real life" pay-off of Hyper-Threading" than the last thing you should be worried about is high memory speeds....you just won't notice a difference. Better to push the CPU as high as possible and relax the memory a bit.

to OCForums

 

[IanM]

All depends on your definition of "home user".

yeah, sorry I was going to try and define that more but got called away.

The demanding applications will be games with anti-virus in the background. I do a bit of graphics editing with GIMP and honestly it's very rare for anything to be doing serious number crunching in the background. Bottom line: I'm struggling to see any real justification (for my usage) in keeping the 860 and Hyper-Threading, right now it just looks like a bigger number and extra feature listed on the box.

If I could be convinced that Hyper-Threading is beneficial for running anti virus while playing games then that would be something at least, still even then it seems like clutching at straws.

Overall, I personally think you're a bit too concerned with high memory speeds.

Maybe, for sure it started out as a case of trying to push this as high as it would go, just for the sake of doing it and to learn about the parameters of overclocking - which is still new to me. The end game was always to run something more relaxed and give some thought to power consumption and long term usage.

That said, the black screen resets without warning have been bugging me a lot as I can't pin this down to anything really definite. It does bother me slightly that by running lower clocks the problem may not be fixed, merely hidden and rarely occuring

 

[MIAHALLEN]

If I could be convinced that Hyper-Threading is beneficial for running anti virus while playing games then that would be something at least, still even then it seems like clutching at straws.

Of course HT will provide slightly more longevity, but other than that, no...sounds like it won't do much for you. Fast storage will provide you the biggest bennefit with the virus scanning you're concerned about.

Maybe, for sure it started out as a case of trying to push this as high as it would go, just for the sake of doing it and to learn about the parameters of overclocking - which is still new to me. The end game was always to run something more relaxed and give some thought to power consumption and long term usage.

Ah! I totally understand

That said, the black screen resets without warning have been bugging me a lot as I can't pin this down to anything really definite. It does bother me slightly that by running lower clocks the problem may not be fixed, merely hidden and rarely occuring

Sorry, I missed this on my first read of the thread. What PSU are you using?

 

[IanM]

Sorry, I missed this on my first read of the thread.

no worries, it's a pretty long old post with lots of points that may or may not be important

Sorry, I missed this on my first read of the thread. What PSU are you using?

It's a Seasonic X-750, so it ought to be fine. It had crossed my mind that it may be faulty. I have tried 6-8hr runs of IBT on stock settings and basic OC (1600MHz memory preset) That worked fine. I guess I need to try a more sustained load, will see if I can push a heavier OC on the CPU for a long run, but relax the memory timings at the same time.

Actually I just thought, I could up the load using the graphics card (5850 Toxic) What's a good CPU + GPU burn test?

 

[EarthDog]

GPU = Furmark.

 

[Brutal-Force]

As far as your concern between the i5 750 and the i7 860, I think it really just comes down to price, in reality if you do a little price checking, you can typically get a i7 for about $30-$50 more than the i5. I figure if the price difference is that small and it doesn't hurt your wallet, then go for the i7.

In terms of multi tasking, you would be hard pressed to use all the processing power of the i7. And if you were even close, then your probably using the wrong platform anyways. I can download 15 Movies, Encode 500 songs with Virus program running in the back ground and a Multi-Core usage Game and the i7 won't blink. The i5 probably won't either...... yet.

As far as memory goes, don't push your memory, buy memory that gives you breathing room. The 0.00302ms time is not even noticeable even if you were encoding 300 Blue rays videos.

As for the screen going black, you might want to check that your drivers are the newest, maybe get a multimeter and check your PSU. While 750W might be enough to run your machine, if its not a quality PSU, then you might be pushing the ragged edge. These chips consume alot of power as well as the 5850.

 

[IanM]

As far as memory goes, don't push your memory, buy memory that gives you breathing room.

That was part of my rationale for getting the HyperX - it's capable of 2000Mhz CL8 at 1.65V, but only needs 1.5V at 1600MHz. Figured anything in between buys me high BCLK with the RAM coping easily, and if I'm really lucky the voltage my be low enough to use it with the next gen Intel.

While 750W might be enough to run your machine, if its not a quality PSU, then you might be pushing the ragged edge. These chips consume alot of power as well as the 5850.

Survived 30-40 min of Furmark running simultaneously with IBT and a modest overclock, but I think I need to use really stable settings and try a long run at this, just in case there is a fault when the PSU increases load or perhaps changes the fan speed.

As far as your concern between the i5 750 and the i7 860, I think it really just comes down to price, in reality if you do a little price checking, you can typically get a i7 for about $30-$50 more than the i5. I figure if the price difference is that small and it doesn't hurt your wallet, then go for the i7.

I'm in the UK so price difference is roughly £65-£75, or in US $100-$115. Price alone make the i5 750 the easy choice - though I don't upgrade often.

Having gone back to basics a little with the 860 and the overclock, it does seem as though the 860 needs a fixed multiplier (for stability) sooner than the 750, so perhaps one way to look at it is a choice between Hyper-Threading or Turbo mode