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Vendetta

Vendetta

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Technically not a nice idea, since you'd likely need to set a voltage "too high" for the 1.5V ones in order to get the 1.65V ones to be stable, ie: around 1.65V.

Whilst overclockers often push memory to that level, it's not ideal as adds electrical stress and heat that can be expected to shorten the product life; the question is by how much!?

So, most likely will work, and if you are not overly worried about potential shorter life then give it a go. (Presume you already have both sets, can't RMA as too old, really need 8GB and don't want to buy new)....

If you do try, would be good to see how much below 1.65V you can go and still have stability. Less voltage is better.

VERY IMPORTANT:
For P55 etc boards, you must not put memory voltage >0.5V above "QPI/CPU Vtt" voltage, which is normally 1.1V.
So you'd usually have to increase Vtt when you increase memory voltage, especially for memory voltage above 1.60V.
(Check what your BIOS is set to).
Of course, increasing Vtt then means you are electrically stressing the CPU a bit more. So higher CPU temps etc.

Intel Spec for i5-750/i7-860 CPU, as far as I can tell, says absolute max:
Vtt 1.21V (normal spec is 1.1V)
mem voltage 1.65V (normal spec is 1.5V)
So, anything above normal can lead to some shortening of life, and I presume anything above these max values potentially leads to a very short life.
 
Thank you for the reply, you definitely answered my question.

Fortunately, I don't have the second set of memory. It just seemed to be a good deal, with the timings and speed being the same as what I had, I thought it may work. I'd prefer to spend an extra $20 and match the memory I already have.

Thanks for the info on the P55 boards. I plan to do a very moderate OC on my i5 760, so I appreciate the heads up.
 
Vendetta said:
... I'd prefer to spend an extra $20 and match the memory I already have.
Click to expand...

Nice. Definitely worth it for the peace of mind and even more so for less complications as you plan a bit of overclocking!

FWIW; I just recently semi-finalized my modest OC:
- 3.2GHz (160x20)
- Memory x10 = 1600MHz,
Memory.. my RipJaws are rated at 1333MHz CAS8.
Using 10-8-8-29 or something like that at 1600. Not tested whether can tighten up timings or reduce freq with even more aggressive timings, as either way it's fast enough for me.
Decided to only use standard voltages everywhere (had to turn off Turbo to be stable with IntelBurn).
 
humph said:
Vendetta said:
... I'd prefer to spend an extra $20 and match the memory I already have.
Click to expand...

Nice. Definitely worth it for the peace of mind and even more so for less complications as you plan a bit of overclocking!

FWIW; I just recently semi-finalized my modest OC:
- 3.2GHz (160x20)
- Memory x10 = 1600MHz,
Memory.. my RipJaws are rated at 1333MHz CAS8.
Using 10-8-8-29 or something like that at 1600. Not tested whether can tighten up timings or reduce freq with even more aggressive timings, as either way it's fast enough for me.
Decided to only use standard voltages everywhere (had to turn off Turbo to be stable with IntelBurn).
Click to expand...

Are you still running the F9 bios, or is your sig outdated?

What kind of temperature rise did you see on your CPU OC?
 
Ah..good catch, I'm on F11 now. (Might go back to F9...we'll see...).

On load temps as shown by iStat (OSX) or RealTemp (Win) are approx:
65C Prime95 OSX (compared to 60C before overclock)
68C IntelBurn WinXP
20C approx Ambient. Idle starts around 33C, but generally around 40 after high activity and a few mins cooling down.
If I open case, then takes about 5C off, as not the best case for airflow.
Mugen 2 rev B on CPU.

I would not be surprised if both temp readings are a bit wrong (too high?) since at one point when pushing past limits, I was getting to 80 C in WinXP before the 70 C CPU BIOS alarm went off. So am pretty happy with the way it is now.
 
Should the i5 760 overclock the same as the 750?

Do you have the same RAM as me (RipJaw 1333)? You OC'd it to 1600?
 
i5-760 OC....I guess same sort of results/headroom as the 750, as a quick google shows it's same 45nm construction, so looks like Intel just are upping the multiplier one level to get 2.8GHz standard.

My memory is the 1333MHz 8-8-8-24 Ripjaw (blue heatsink). So, yes it can run at 1600MHz, but running with backed-off the timings (10-8-8 currently).
EDIT: 8 cycles at 1333MHz approx same time as 10 cycles at 1600MHz.
Although possibly could get it to run "faster" (tighter timings) by adding some more volts. Certainly "real" 1600MHz stuff rated 7-8-7 @ 1.6V or whatever is clearly faster (or is easier to get there as it's all baked into the profiles..although I presume they do screening to select out the faster chips, or perhaps that's just marketing gibberish!).

Anyway, if you've already got the red Ripjaws 1.5V @ 9-9-9-24 timings, well you can either use the x10 memory multiplier and try to push the memory frequency over 1333MHz (as you increase the BCLK above 133MHz) by loosening timings..or adding a bit of memory volts to try to maintain timings; or use x8 multiplier and run at or below 1333MHz and try reduced timings (unless you push BCLK high, like >=180MHz, in which case even a x8 multi is going to force memory above 1333MHz).

Sorry if you already know all that stuff..... It's just a (time-consming) balancing act!
 
humph said:
i5-760 OC....I guess same sort of results/headroom as the 750, as a quick google shows it's same 45nm construction, so looks like Intel just are upping the multiplier one level to get 2.8GHz standard.

My memory is the 1333MHz 8-8-8-24 Ripjaw (blue heatsink). So, yes it can run at 1600MHz, but running with backed-off the timings (10-8-8 currently).
EDIT: 8 cycles at 1333MHz approx same time as 10 cycles at 1600MHz.
Although possibly could get it to run "faster" (tighter timings) by adding some more volts. Certainly "real" 1600MHz stuff rated 7-8-7 @ 1.6V or whatever is clearly faster (or is easier to get there as it's all baked into the profiles..although I presume they do screening to select out the faster chips, or perhaps that's just marketing gibberish!).

Anyway, if you've already got the red Ripjaws 1.5V @ 9-9-9-24 timings, well you can either use the x10 memory multiplier and try to push the memory frequency over 1333MHz (as you increase the BCLK above 133MHz) by loosening timings..or adding a bit of memory volts to try to maintain timings; or use x8 multiplier and run at or below 1333MHz and try reduced timings (unless you push BCLK high, like >=180MHz, in which case even a x8 multi is going to force memory above 1333MHz).

Sorry if you already know all that stuff..... It's just a (time-consming) balancing act!
Click to expand...

Thanks again humph!

So, I'm familiar with the basics of overclocking, and havwcome up with this tentative plan. Just wanted to run it by someone to be double checked. I'm not looking to max out because I'm still on stock cooling. Basically my pan is to not increase any voltage, as I want to keep the heat to a minimum and don't think my OC will need more juice.

I'm thinking to drop CPU multiple to 19, BCLK to 168 or so, and drop RAM multi to 8. Won't change ANY other settings accept the Uncore frequency. As far as I can tell thus will give me a CPU freq of approx. 3.2GHz and keep my RAM at 1333. Obviously, its a bit of a balancing act because my RAM isn't 1600.

I know the proper way to achieve max OC isto drill through one thing at a time, and I'm familiar with that process, but my OC is only 400MHz and seems pretty mild to what others are doing. Am I correct with this logic, and is my plan good enough to continue with?

Also, I don't have a windows partition, so what's the best method for stress test? I'm familiar with memtest, and know you can run Prime through wine and such, but are there better options? Thanks for the help! I look forward to any answers, so I can get started on this OC. :headbang:
 
I didn't think it's possible to change the Uncore freq multiplier (well, at least not on my MB and i5-750 CPU), so you get x16 period.

But you may want/need to lower the QPI multi to x32 to avoid that freq getting too high.
So, yeah the +400MHz on the CPU is not a big deal, it's the QPI etc that may start to get flaky as BCLK goes >160 (w/o voltage changes).

Guess you'll only know when you try ;)
Good Luck!
 
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