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My PC-8500 memory is PC-6400..

1278 Views 16 Replies 3 Participants Last post by  98uk, 
98uk
I bought some new RAM from www.ebuyer.com. I purchased the following:

Quote:
1 x OCZ 4GB Kit (2x2GB) DDR2 1066MHz/PC2-8500 Reaper Memory HPC Edition Dual Channel
However, having had them running stable at 1120mhz for a few weeks, I have just noticed in Everest that apparently these modules are:

Quote:
Memory Speed:DDR2-800 (400 MHz)
Profile Name:High Frequency
Optimal Performance Profile:Yes
Memory Speed:DDR2-1066 (533 MHz)
Memory Timings:5-5-5-15 (CL-RCD-RP-RAS)
Does this mean they are PC-6400 modules or what???

also

I had some Geil Ultra 800mhz RAM running at about 1020mhz which was obviously limiting my overclock from going higher. At this speed it used 5-5-5-15.

I fitted some new OCZ Reaper 1066mhz modules and pushed them to 1120mhz, but never changed my timings. I now noticed on Ebuyers site, they are rated at 1066mhz with 5-5-5-18.

Is this likely to be holding my OC back as i seem to not be able to get 3.8ghz whatever!
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Acoma_Andy
Well it's impossible that your memory is holding back. Because at your current FSB, running 1:1 would give you 822mhz memory. That means there still is a lot of headroom for the memory.

And it's normal that 1066 modules are being seen as 800, since that is the standard specification. PC8500 sticks are essentially overclocked PC6400 sticks, and most good PC6400 can easily overclock to PC8500 speeds.
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98uk
It could well be the memory. My P5Q Deluxe has a bug whereby it will not POST on the first memory strap. Therefore i have to use the second memory strap which will always be slightly overclocked.

Also, i'm using a 8x multiplier meaning the FSB is higher than normal, 467mhz to be precise.
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Acoma_Andy
Quote:

Originally Posted by alex98uk View Post
It could well be the memory. My P5Q Deluxe has a bug whereby it will not POST on the first memory strap. Therefore i have to use the second memory strap which will always be slightly overclocked.

Also, i'm using a 8x multiplier meaning the FSB is higher than normal, 467mhz to be precise.
It's the first time I hear of that bug. In another rig I have a P5Q Pro, and it had some issues with certain memory modules as well but a bios update fixed it. That rig runs fine with 1:1.

Perhaps you could OC the memory a bit further if you raise the performance level.
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98uk
Yeah, i've used multiple BIOS's from Asus, usually the latest one available, but still, it just doesn't POST on the first strap.

Could setting the timings at 5-5-5-15 instead of the 5-5-5-18 that Ebuyer recommend cause instability?
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whe3ls
about your your detecting at pc 6400. they are set to boot that a lower speed then what they are binned at.
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Acoma_Andy
Quote:

Originally Posted by alex98uk View Post
Yeah, i've used multiple BIOS's from Asus, usually the latest one available, but still, it just doesn't POST on the first strap.

Could setting the timings at 5-5-5-15 instead of the 5-5-5-18 that Ebuyer recommend cause instability?
18 is a bit looser then 15, so it might allow for a higher overclock also. You could set the memory to 6-6-6-18, but then your bandwith will be a lot less.

What is your current PL (performance level) at? That has a pretty big impact.
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98uk
Current performance level is: 08.

I actually set that because I was told to in a P5Q overclocking guide, and it worked. Is this correct?

I will try changing from 15 to 18.
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Acoma_Andy
Quote:

Originally Posted by alex98uk View Post
Current performance level is: 08.

I actually set that because I was told to in a P5Q overclocking guide, and it worked. Is this correct?

I will try changing from 15 to 18.
8 is pretty tight at that memory speed and FSB, try setting it to 9. With my UD3P at 471, if I want 1FSB higher, I have to set PL to 9 also.
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98uk
Okay, i shall try that. Is 10 not an option?
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Acoma_Andy
Quote:

Originally Posted by alex98uk View Post
Okay, i shall try that. Is 10 not an option?
Sure, 10 is also an option, but you are sacrificing a lot of bandwith for a tad higher CPU clock.

You could test the difference with the Everest memory benchmark.
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98uk
Can you explain how these ""performance levels" work. The higher i set them, what happens?

What is the limit, 10? Surely a higher CPU clock is more beneficial than the RAM bandwidth that is given up?
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Acoma_Andy
Quote:

Originally Posted by alex98uk View Post
Can you explain how these ""performance levels" work. The higher i set them, what happens?

What is the limit, 10? Surely a higher CPU clock is more beneficial than the RAM bandwidth that is given up?
Not sure if there is a limit to it, but 11 or 12 is already pretty loose. Basically what it does is give your memory modules a bit more room to breathe at the cost of memory bandwith.

Not sure in your case if it's beneficial or not, you'd have to test the difference.
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98uk
Well, i have loosened timings from 15 to 18 and changed performance level to 09. I raised the FSB from 465 (3.74ghz) to 475 (3.8ghz) and Vcore from 1.45v to 1.5v (raised temps by about 4c
)

It's certainly stable enough in Windows to be on the Internet, listening to music and office processing, so it can't be far off complete stability. Last time i tried, it usually failed Prime95 after about 20 minutes (in a BSOD).

The reason I was using an 8x multiplier was that it made a huge difference to my 3Dmark06 scores (raising from 16,800 to 17,100), so it did do something. Plus, I heard the P5Q can bench stable at over 500mhz FSB.
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98uk
...and still it will not stay stable...
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Acoma_Andy
Quote:

Originally Posted by alex98uk View Post
...and still it will not stay stable...
But will it pass memtest?
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98uk
It failed Prime's RAM test when at 3.8ghz, but fine at 3.72ghz
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