Unable to get a stable OC but I can't see why not.

[Fang508]

So I am running a Asus p6t lga 1333 mobo with a 3.6ghz x5687 quad core xeon and new 3x4gb 2400mhz c11 evga superSC ram. I bought the ram for low timings I know I can't get a high ram speed. I am trying for a 900mhz~ 1ghz OC. So far at 4.50ghz I can boot into windows 7 but every time i run prime 95 on blend i get "prime 95 has stopped working" message a few moments later. All other torture tests seem to work longer. From what I have read this is probably a ram issue but all my ram settings are fine.. I have some pictures of my bios maybe you can tell me what I am doing wrong.. Thanks

 

[Lochekey]

Are you running prime95 with the blend test or the small fft test?

 

[Fang508]

All of them actually. Small fft lasts much longer than blend. I am using P95 x64 ver 26.

 

[Lochekey]

Can you list you full system specs. Also, what temps are you seeing while running prime 95

 

[Fang508]

Can you list you full system specs. Also, what temps are you seeing while running prime 95

Asus P6T LGA 1366 Motherboard
Intel Xeon x5687 3.6ghz Quad core CPU
3 x 4GB EVGA SuperSC CL11 2400mhz DDR3
Rosewill Green 630w PSU

Prime 95 max temps are around 80~85c

 

[wingman99]

Your memory is 2400 speed? DDR Double Data Rate, so you need 1200MHz setting. Link: https://en.wikipedia.org/wiki/CAS_latency

 

[Fang508]

Your memory is 2400 speed? DDR Double Data Rate, so you need 1200MHz setting. Link: https://en.wikipedia.org/wiki/CAS_latency

Yes, I already know that. And if you had read my first post, you would have found that I am aiming for 800mhz. Also, the x5687 IMC cannot handle 1200mhz maybe but not easily even 1000mhz. and like I said in my first post, I only bought this ram for tighter timing. Do you know why this setup is crashing / giving me rounding errors in prime95 but not a BSOD?

 

[wingman99]

In your Screenshot I see DDR3 1674 MHz not 1200MHz?

 

[Fang508]

In your Screenshot I see DDR3 1674 MHz not 1200MHz?

1600/2 is 800 so 837mhz x2 is 1674mhz which = double data rate. Are you trolling? Really? what is the possibility of 2400mhz ram running at 3300mhz speed at CL10?

 

[Lochekey]

Have you tried reducing the memory multiplier and then running prime95. If it still fails with a slower memory speed it points to a slightly unstable core. I see that you are already pushing 1.45 vcore, as I am not intimately familiar with this platform i cannot rightly recommend pushing it further. Instead I would try reducing bclk slightly to see if it stabilizes.

 

[wingman99]

1600/2 is 800 so 837mhz x2 is 1674mhz which = double data rate. Are you trolling? Really? what is the possibility of 2400mhz ram running at 3300mhz speed at CL10?

I'm not trolling I'm trying to help you. In your first post you have DDR3 2400 speed memory /2 is 1200Mhz command rate.

DDR3 2400 is not the MHz like you have in your first post, it is the rated speed of DDR, the MHz is the Bus speed of the memory, so it is half the speed of the rated memory.

Can you imagine 2400MHz buss speed X 2 = DDR3 4800 SPEED, EVGA has it incorrect.

I will link this again take a look at memory speeds https://en.wikipedia.org/wiki/CAS_latency

 

[Fang508]

I'm not trolling I'm trying to help you. In your first post you have DDR3 2400 speed memory /2 is 1200Mhz command rate.

DDR3 2400 is not the MHz like you have in your first post, it is the rated speed of DDR, the MHz is the Bus speed of the memory, so it is half the speed of the rated memory.

Can you imagine 2400MHz buss speed X 2 = DDR3 4800 SPEED, EVGA has it incorrect.

I will link this again take a look at memory speeds https://en.wikipedia.org/wiki/CAS_latency

I do know that yes you are right about rated speed=/=mhz, however the Asus bios is showing mhz where it should show rate which is probably where the confusion is. In cpu-z it shows 800mhz while bios shows 1600mhz. Anyways I am going to up the cpu multi and drop the base clock and ram multi and see what happens.

 

[RJARRRPCGP]

Make sure Prime95 is updated to 28.6 with the "Prime95 has stopped working" Windows error...

 

[wingman99]

I do know that yes you are right about rated speed=/=mhz, however the Asus bios is showing mhz where it should show rate which is probably where the confusion is. In cpu-z it shows 800mhz while bios shows 1600mhz. Anyways I am going to up the cpu multi and drop the base clock and ram multi and see what happens.

I see what your are saying since you see 800Mhz in CPU-Z. like you said the memory controller is rated for DDR3 800/1066/1333. So you should try and see if the memory works well at rated memory controller speed, if you have not done this already.

 

[Fang508]

Well here is a bit of a mystery. At the moment I am running my Xeon x5687 @ 4312mhz 154mhz bclk x 28 multi 1.425v Vcore 1.425v 6786mhz QPI with Ram @ 616mhz (1232) CL10 2T 1.68v & Uncore @ 2464mhz. I ran LinX and Prime 95 at the same time for 7 hours straight without crashes, errors, or a BSOD. But when I ran OCCT it gave me an error within 8 mins. So... what now? How does 8 mins of OCCT = > 7hours of linX & P95 simultaneously?

 

[wingman99]

Stress testing programs stress processors in different ways effecting transistors that are not effected with other stress test programs. Prime95 for example is mostly FPU and some integer, OCCT LINPACK is a software library for performing numerical linear algebra. Add more voltage to your core and see if OCCT will pass.

Also do you have OCCT v4.4.2?

 

[Fang508]

Stress testing programs stress processors in different ways effecting transistors that are not effected with other stress test programs. Prime95 for example is mostly FPU and some integer, OCCT LINPACK is a software library for performing numerical linear algebra. Add more voltage to your core and see if OCCT will pass.

Also do you have OCCT v4.4.2?

Well I bumped Vcore to 1.430 and OCCT lasted 4 hours before getting an error. I bumped it to 1.438 and now testing again to see what's what. How long is good enough test for OCCT? 8 hours? Is a 700mhz overclock too optimistic? Granted it's not an intel but, I have a Phenom II 805 x4 2.5ghz lying around that I overclocked 900mhz using AMD's max safe voltage without issues aswell as the northbridge.

 

[wingman99]

It's up to you how long you want to run OCCT, I would only run for 8 hours.

0.750V-1.350V is the stock VID range of x5687. When you overclock you have to go into the danger zone, we around here say 1.44v maximum is fine for 24/7 overclock. Just remember to tell your self that you are increasing the processor speed past Intel's stable retail speed no guarantee on what it will do.

 

[Fang508]

It's up to you how long you want to run OCCT, I would only run for 8 hours.

0.750V-1.350V is the stock VID range of x5687. When you overclock you have to go into the danger zone, we around here say 1.44v maximum is fine for 24/7 overclock. Just remember to tell your self that you are increasing the processor speed past Intel's stable retail speed no guarantee on what it will do.

Well I am running 1.44v Vcore and it was still testing at 13hours OCCT stable and max temp was 73c but average was much less like 65c~68c so I went ahead and saved a profile of it in my bios. Now I am working on ram and timings. I tried going another 3~ mhz bclk and it would fail OCCT and I don't want to go over 1.44v -_- so I guess I am stuck with a 700mhz overclock.

 

[wingman99]

I think you are doing fine. With the voltage and clock you have tried it just shows the CPU is not willing to increase to a great extent, however 700Mhz overclock is good.