E8400 @ 4.5GHz Realistic 24/7?

[TexasOC]

to be honest the E8400 LOVES FSB, its just the board pretty much

ive seen many E8400 E0 steppings go towards 600 FSB on a T-Power I45 ( Biostar )

Is there any feeling for what is a safe P45 MCH core voltage? On a lot of these 500MHz+ FSB runs they are running the MCH core voltage north of 1.4V. Given that the stock voltage is 1.1V and ABS MAX is 1.2V, 1.4V seems like *a lot*.

-Mike

 

[freeagent]

1.4 should be ok, i would think. i think my rampage has a core of 1.1 or 1.2v, and i shoved 1.4-1.55 into it routinely, the same goes for this board too, it has actually spent the better part of 2 years bouncing between 1.4-1.55 as well.

 

[TexasOC]

One thing about this GA-EP45-UD3P is it appears to be very sensitive to bios settings for stability @500MHz FSB -- especially the CPU and MCH reference voltages. I've never tried running the FSB up this high before, perhaps this is par for the course and I'm just learning that now.

Anyway, I managed to get 500MHzFSB x 6 to pass an overnight P95 test for 10 hours before I stopped it. Getting it there was a challenge as it took a while to get bios settings that allowed it to boot XP, let alone run P95. Note that 500MHz x 6 for an E8400 is only overclocking the FSB, core speed is stock.

Next step is 500MHz x 8. We'll see if that can pass while I'm at work today.

-Mike

 

[Bojcha]

One thing about this GA-EP45-UD3P is it appears to be very sensitive to bios settings for stability @500MHz FSB -- especially the CPU and MCH reference voltages. I've never tried running the FSB up this high before, perhaps this is par for the course and I'm just learning that now.

Anyway, I managed to get 500MHzFSB x 6 to pass an overnight P95 test for 10 hours before I stopped it. Getting it there was a challenge as it took a while to get bios settings that allowed it to boot XP, let alone run P95. Note that 500MHz x 6 for an E8400 is only overclocking the FSB, core speed is stock.

Next step is 500MHz x 8. We'll see if that can pass while I'm at work today.

-Mike

And how you do that.. what bios settings?
Today i mount my new Cooler and @ 4GHz (445x9) from 61c i get a 51c...
And again i tryed only to push to 4.14GHz (460x9) and p95 always crash.
again start to up vcore from 1.4 to 1.48 .. and always same result.
Erlier .. i tryed a (6*470) but still crashing .. like mobo don't like fsb over ~460
at 4Ghz and vcore 1.376v is always super stable.

 

[jason4207]

One thing about this GA-EP45-UD3P is it appears to be very sensitive to bios settings for stability @500MHz FSB -- especially the CPU and MCH reference voltages. I've never tried running the FSB up this high before, perhaps this is par for the course and I'm just learning that now.

Anyway, I managed to get 500MHzFSB x 6 to pass an overnight P95 test for 10 hours before I stopped it. Getting it there was a challenge as it took a while to get bios settings that allowed it to boot XP, let alone run P95. Note that 500MHz x 6 for an E8400 is only overclocking the FSB, core speed is stock.

Next step is 500MHz x 8. We'll see if that can pass while I'm at work today.

-Mike

Are you testing w/ small-fft, large-fft, or blend? I recommend running large-fft while pushing the FSB like you are. Once that's stable you can up the multi and run small-fft to stress the CPU.

The P45 is on a smaller process than P35/X38/X48...65nm vs 90nm. As such the P45 needs less vNB than the others. You can push 1.45-1.5v if you want and temps are good, but you really shouldn't need to. 1.3v should take you a long way, and I've found P45 to be particularly picky...too much vNB can actually make you less stable. There is definitely a sweet spot, and vtt also interacts strongly w/ vNB and NB stability.

 

[TexasOC]

And how you do that.. what bios settings?
Today i mount my new Cooler and @ 4GHz (445x9) from 61c i get a 51c...
And again i tryed only to push to 4.14GHz (460x9) and p95 always crash.
again start to up vcore from 1.4 to 1.48 .. and always same result.
Erlier .. i tryed a (6*470) but still crashing .. like mobo don't like fsb over ~460
at 4Ghz and vcore 1.376v is always super stable.

I'm referring to the bios settings specifically for my mobo (Gigabyte UD3). They are specific to this board will probably only be helpful if you are running the same board. This board (and maybe other P45 boards) can be picky about voltage values when overclocking.

The values I'm playing with are termination voltages and references between the MCH and CPU. I'll post a full set once I have more success.

-Mike

 

[TexasOC]

Now that's what I'm talking about!

Are you testing w/ small-fft, large-fft, or blend? I recommend running large-fft while pushing the FSB like you are. Once that's stable you can up the multi and run small-fft to stress the CPU.

The P45 is on a smaller process than P35/X38/X48...65nm vs 90nm. As such the P45 needs less vNB than the others. You can push 1.45-1.5v if you want and temps are good, but you really shouldn't need to. 1.3v should take you a long way, and I've found P45 to be particularly picky...too much vNB can actually make you less stable. There is definitely a sweet spot, and vtt also interacts strongly w/ vNB and NB stability.

Blend, I believe. I'll check when I can. I had some pretty good success. Yes, vtt, as well as the references, seem to have a large impact.

ETA: P95 Blend. Passed 4.40G/518/500 for 17.25 hours before I stopped it. Core temps were peaking at about 62C.

-3.0GHz/500FSB passed P95 for 10 hours before stopping.
-4.0GHz/500FSB passed P95 for 12 hours before stopping after upping the CPU core voltage. I had previously thought I could do this a stock voltage, but at stock it would fail P95 in a little over an hour.
-4.4GHz/518FSB has been passing P95 for the last 13 hours and I want to see if it will make it to 24 hours.
-4.5GHz appears to be a no go. I went up to 1.425V with load line enabled and it still failed P95 rather miserable with very high temps (70C). At 4.4GHz, core voltage is 1.4V without loadline and temps are topping out at about 62C.

The high FSB trick is to sort out the FSB first by running the CPU as slow as possible (smallest mult). Once the FSB is stable, then crank up the mult.

My goal was 4.5GHz/500FSB/DDR2-1000 5-5-5-15 on air. I'll take 4.4GHz/518FSB/DDR2-1036 5-5-5-15 on air thank you very much!

Next steps are to test beyond P95 and start knocking down the voltages. The forum postings here, on Hardocp, and Xtremesystems were invaluable in getting this result.

ETA: I haven't had a result this good since the Celeron 300A. Way back when these were all the rage. On a BX board you could easily get one to 450MHz. I even made a version of the Celery Sandwich. This E8400 cost less than the 300A and the mobo cost the same as a BX did back in 1998. An equivalent OC today to the 300A would be getting an E8400 to 4.5G. Very .

-Mike

 

[mick353]

took me ages with a dozen or so hard reboots and even more tweaks and fine tuning and benchmarking etc but I've currently hit 4.5 with 1.5v, 1.49 under load.. very stable .. after reading some of the earlier posts here i might try for 4.6 or 7 but think temps will bite me b4 then..

i did find a few interesting things like MCH even slightly too high will screw with your benches ntm temps and it definately helps to ensure your memory can handle the extra speed before even considering upping the fsb..

anyway found this to be completely stable and i test with prime, tat, occ, 3D06 etc.. unfortunatly i can't really drop the voltage while keeping the speed and i'm happy with the temps maxing at mid sixties so.. ..