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P55-UD4P and 1866 Ram Setting ?? !!!

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April 16, 2010 8:59:20 AM

Hi
I have a P55-UD4P, i5 750 and 2x2GB 1866 Team Memory (TXD36144M1866HC9TC) setup.

I am trying to get full perfomance from my Ram but the default bios is set too 1333.
I have tried enabling XMP but it causes the Pc to crash after 1-2 minutes

Not looking to overclock anything but rather small tweaks to get what i paid for (1866 Ram! :??:  )

Any help would be greatly appreciated
Thanks
a b V Motherboard
April 16, 2010 11:10:13 AM

antony_tem said:
Hi
I have a P55-UD4P, i5 750 and 2x2GB 1866 Team Memory (TXD36144M1866HC9TC) setup.

I am trying to get full perfomance from my Ram but the default bios is set too 1333.
I have tried enabling XMP but it causes the Pc to crash after 1-2 minutes

Not looking to overclock anything but rather small tweaks to get what i paid for (1866 Ram! :??:  )

Any help would be greatly appreciated
Thanks


If you want higher RAM multipilers, buy a Core i7 processor, since those have the upper multipliers unlocked. If you want to overclock instead, do it manually.
April 16, 2010 11:29:23 AM

Crashman said:
If you want higher RAM multipilers, buy a Core i7 processor, since those have the upper multipliers unlocked. If you want to overclock instead, do it manually.


would i be able to achieve 1866 by overcocking since i dont have any extra cooling system?
If so, what parameters do i have to setup in the bios ?
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a c 177 V Motherboard
April 16, 2010 1:19:49 PM

The i5-750 is limited to 6/8/10 memory multipliers, so with a 'stock' Bclk of 133, the best you'll be able to get is 1333; to get roughly 1866, you'd need the Bclk at 186, which would bump your CPU to 3.72 GHz - you'd be back to close to stock by then lowering the CPU multiplier to 15...
April 16, 2010 1:50:07 PM

bilbat said:
The i5-750 is limited to 6/8/10 memory multipliers, so with a 'stock' Bclk of 133, the best you'll be able to get is 1333; to get roughly 1866, you'd need the Bclk at 186, which would bump your CPU to 3.72 GHz - you'd be back to close to stock by then lowering the CPU multiplier to 15...


Thanks
Would lowering the Cpu Multiplier to 15 affect its perfomance ?
a c 177 V Motherboard
April 16, 2010 2:21:08 PM

No it won't, but, then again, neither will you ever 'see' any real-world performance increase by going from the 1333 you'd normally get, to 1866; memory frequency doesn't 'scale' to actual performance on these platforms - just increases the heat load on the memory controller, and makes a terribly large job of 'tuning' the whole shebang!

a c 177 V Motherboard
April 16, 2010 2:38:09 PM

Oh - and before you ask the next question (which everyone does - "Then why do they even make 1866 [or 2000, or 2166...] memory?" - it's a simple four word answer: "they want the money!"

Best solution

a b V Motherboard
April 16, 2010 2:52:05 PM
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antony_tem said:
Thanks
Would lowering the Cpu Multiplier to 15 affect its perfomance ?



When you raise the Base Clock (bclk), understand that that overclocks the entire processor and memory systems.

I believe your stock CPU multi is 20, and the standard bclk setting is 133. 133 x 20 = 2,660. And there is your 2.6Ghz

For Memory it's the same math: The memory divider may be set with 6, 8, or 10. At the stock 133 mhz Base Clock, that nets 798, 1064, and 1333. Your system does not support dividers higher than 10. So the only thing left to change is the Base Clock. But this takes everything else with it.


So - If you raise the Base Clock, then what happens? Let's try 150, so we get nice, neat numbers:

150 bclk x 20 cpu multi = 3,000 for a 3 GHz Processor overclock
150 bclk x 10 memory multi = 1500, for DDR3 1500


Using the 186 number Bilbat gave:
186 x 20 = 3720 for 3.7Ghz (this is a high overlock, by the way: 3.7/2.6 = 42% You may not be able to count on this being stable or sustainable. And certainly not without raising voltages and heat.)
186 x 10 = 1860, for your memorys rated speed.

This is not likely to be stable without superior components, a lot of knowledgeable tweaking, and a superior cooling system. Let me say that again: a 42% overclock is not likely to be stable unless you have superior components, a superior cooling system, and some knowledgeable tweaking.

Therefore, as Bilbat said, you will likely have to LOWER your processor multiplier in order to reach something reliable.

So, let's look at the math again:

At a 186 Base Clock (maybe your motherboard can sustain this... maybe not), we know that your memory will run at 1860 Mhz.

186 x 10 = 1,860, or 1.8 Ghz = Way slower than stock, right?
186 x 15 = 2,790, or 2.7Ghz. = a little faster than stock, but a very mild (2.7/2.6 = 4%) overclock
186 x 17 = 3,162 or 3.1Ghz = A respectable overclock (3.1/2.6 = 19%)



The issue here is you overbought memory for the system you have. By this, I mean your RAM is fast enough that you have to strongly overclock everything else to get to your memory's rated speed.

My personal recommendation is (1) Accept that you overbought and don't worry about it. But if you must, then forget about getting to your memory's "rated" speeds. Rather, split the difference with a comfortable CPU overclock and be secure in the knowledge that any issues are likely not the fault of your RAM.




a c 177 V Motherboard
April 16, 2010 3:09:31 PM

Here's an illustration that sometimes helps with the underlying concepts:
April 16, 2010 3:17:28 PM

Scotteq said:
When you raise the Base Clock (bclk), understand that that overclocks the entire processor and memory systems.

I believe your stock CPU multi is 20, and the standard bclk setting is 133. 133 x 20 = 2,660. And there is your 2.6Ghz

For Memory it's the same math: The memory divider may be set with 6, 8, or 10. At the stock 133 mhz Base Clock, that nets 798, 1064, and 1333. Your system does not support dividers higher than 10. So the only thing left to change is the Base Clock. But this takes everything else with it.


So - If you raise the Base Clock, then what happens? Let's try 150, so we get nice, neat numbers:

150 bclk x 20 cpu multi = 3,000 for a 3 GHz Processor overclock
150 bclk x 10 memory multi = 1500, for DDR3 1500


Using the 186 number Bilbat gave:
186 x 20 = 3720 for 3.7Ghz (this is a high overlock, by the way: 3.7/2.6 = 42% You may not be able to count on this being stable or sustainable. And certainly not without raising voltages and heat.)
186 x 10 = 1860, for your memorys rated speed.

This is not likely to be stable without superior components, a lot of knowledgeable tweaking, and a superior cooling system. Let me say that again: a 42% overclock is not likely to be stable unless you have superior components, a superior cooling system, and some knowledgeable tweaking.

Therefore, as Bilbat said, you will likely have to LOWER your processor multiplier in order to reach something reliable.

So, let's look at the math again:

At a 186 Base Clock (maybe your motherboard can sustain this... maybe not), we know that your memory will run at 1860 Mhz.

186 x 10 = 1,860, or 1.8 Ghz = Way slower than stock, right?
186 x 15 = 2,790, or 2.7Ghz. = a little faster than stock, but a very mild (2.7/2.6 = 4%) overclock
186 x 17 = 3,162 or 3.1Ghz = A respectable overclock (3.1/2.6 = 19%)



The issue here is you overbought memory for the system you have. By this, I mean your RAM is fast enough that you have to strongly overclock everything else to get to your memory's rated speed.

My personal recommendation is (1) Accept that you overbought and don't worry about it. But if you must, then forget about getting to your memory's "rated" speeds. Rather, split the difference with a comfortable CPU overclock and be secure in the knowledge that any issues are likely not the fault of your RAM.



Thanks for the great explanation
I tried changing the base clock to 186 and the cpu multiplier to 15. but saw my cpu temp rise from 45 to 85 :ouch: 
so i guess there not much to do with what i have.

Thanks again
a c 177 V Motherboard
April 16, 2010 3:36:05 PM

Almost any kind of 'fiddling with' any Intel pretty much requires that you dump the original 'rotary postsge stamp' stock coolers - BUT - you don't need to spend a lot; nearly any aftermarket cooler will have two or three times the heat-moving ability; only need to consider the top end coolers if you're planning at or over 4GHz, 24/7 with a relatively heavy workload!
a b V Motherboard
April 16, 2010 10:01:11 PM

antony_tem said:
Thanks for the great explanation
I tried changing the base clock to 186 and the cpu multiplier to 15. but saw my cpu temp rise from 45 to 85 :ouch: 
so i guess there not much to do with what i have.

Thanks again


It sounds like your MOTHERBOARD BIOS assumes you're trying to overclock the CPU and has adjusted the core voltage accordingly. Try these settings:

VCore 1.25V
Uncore: 1.35V (sometimes called QPI/DRAM, IMC, or similar)
VDIMM: 1.65V

with your 185x15 setting.
April 19, 2010 3:35:59 PM

Best answer selected by antony_tem.
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