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Confusion about Dram frequency and cpu clock - please help

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August 4, 2009 4:19:30 PM

Hi all,

Firstly many thanks for all the wonderful threads. I've learned a lot by reading your thoughts.

Still I'm confused about something - I tried searching but couldn't find a specific answer.

I'm overclocking my lowly E2220 from default 2.4 ghz to 3 ghz. This was done on a Gigabyte 945P-S3 mobo.

I was able to get CPU to 3.4 ghz - a full 1 gig over normal spec - so I thought: horrah I'm lucky to have such a chip.

Note this is done using the stock hsf by intel and using speedfan and/or bios settings to keep temps reasonable - never got over 60 C at full load.

I'm using PC-6400 memory - DDR2 667.

I was able to get cpu to 3.4 ghz only if the dram frequency (from CPUZ) runs at 280 mhz or so.

I am also able to get cpu to 3 ghz with dram frequency of 333 mhz.

So here are my 2 basic questions. Am I better off to run cpu at 3 ghz to get better bandwidth and usage from memory or can I run it at 3.4 and have to drop dram frequency to 280.

My memory (according to SPD tab on CPUZ) can run at max frequency of 400 mhz.

But for the life of me I cannot get it to run at this frequency. I've tried changing mem timings, increase voltage to ram, even cpu, and different ratios in bios and all other combinations but still I cannot run it at 400 mhz and get a decent overclock from CPU.

What am I doing wrong? Please can you advise?

Many thanks in advance :) 
hany
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August 4, 2009 7:05:38 PM

Did you unlink your memory?
August 4, 2009 8:48:10 PM

overshocked said:
Did you unlink your memory?


Thanks for the quick reply overshocked :) 

By unlock memory do you mean set the dividers? I tried ratios of 1:1, 2.0, 2.5 and probably others to no avail :( 

Shouldn't my memory run at 400 mhz? Or at least up to it?

No matter what ratios I've tried (with various bus clocks) I can't get it to run past 333mhz, and the seamingly ideal 3.4 ghz of the cpu forces the memory to run at 280 mhz or so, well below 400 :( 

Any ideas my friend?
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August 5, 2009 3:25:05 PM

Anyone please?
August 6, 2009 1:11:25 PM

Anyone?

My ddr2 - 800 ram should easily handle cpu fsb of up to 400 (with 1:1, or 2.0 divider as gigabyte calls it).

And I've had the cpu fsb up to 333 or so and no matter what dividers I set it 'reverts' my ram to 280mhz.

As a result I've accepted a balanced approach: 250 cpu fsb, and 2.66 divider run ram at 333mhz. Still a far cry from its supposed 400mhz :( 

Do you think my ram is the problem?

Which is better for higher PC performance: Higher processor fsb and lower memory frequency/bandwidth OR lower processor fsb and higher memory bandwidth?

Thanks in advance.
August 7, 2009 10:03:51 PM

Guys please - anyone?
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August 8, 2009 2:54:58 AM

Did you check for a memory hole? Try setting the FSB right to 400MHz. Relax the timings down to 5-5-5-18, and up the Vram to whatever your ram is supposed to be. Drop the CPU multiplier down to 6 or 7. (don't worry about it right now, we are checking to see if the system can handle 400MHz.) I'm not sure you hit 400MHz FSB with a 945 chipset. Thats probably much to much for that chipset. If you had a good 975/965 or the P35 it would be doable.

As for which is better, probably the faster CPU speed. For gaming, the faster CPU speed will win out.
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a b K Overclocking
August 8, 2009 5:17:22 AM

hanybanoub said:
Hi all,

Firstly many thanks for all the wonderful threads. I've learned a lot by reading your thoughts.

Still I'm confused about something - I tried searching but couldn't find a specific answer.

I'm overclocking my lowly E2220 from default 2.4 ghz to 3 ghz. This was done on a Gigabyte 945P-S3 mobo.

I was able to get CPU to 3.4 ghz - a full 1 gig over normal spec - so I thought: horrah I'm lucky to have such a chip.

Note this is done using the stock hsf by intel and using speedfan and/or bios settings to keep temps reasonable - never got over 60 C at full load.

I'm using PC-6400 memory - DDR2 667.

I was able to get cpu to 3.4 ghz only if the dram frequency (from CPUZ) runs at 280 mhz or so.

I am also able to get cpu to 3 ghz with dram frequency of 333 mhz.

So here are my 2 basic questions. Am I better off to run cpu at 3 ghz to get better bandwidth and usage from memory or can I run it at 3.4 and have to drop dram frequency to 280.

My memory (according to SPD tab on CPUZ) can run at max frequency of 400 mhz.

But for the life of me I cannot get it to run at this frequency. I've tried changing mem timings, increase voltage to ram, even cpu, and different ratios in bios and all other combinations but still I cannot run it at 400 mhz and get a decent overclock from CPU.

What am I doing wrong? Please can you advise?

Many thanks in advance :) 
hany


First of all, your 945P chipset is only designed to run the memory up to DDR2-667 (333 MHz clock), so I'd wouldn't put much effort into going faster. Second of all, if your memory is running in dual-channel mode you don't need it to go any faster.

According to my calculations you probably reached around 310 MHz FSB clock. You don't need more than 310 MHz DRAM clock (DDR2-620) to match that, bandwidth and clock speed wise, with dual-channel mode making up the QDR/DDR difference.

August 8, 2009 10:13:59 AM

thank you both for your response :) 

4745454b, I've checked my 2GB of memory in bios, matches windows readings.

I don't have access to a multiplier on that chipset, but I've tried fsb of 400, memory divider 1:1/2.0, loosened timings to 5-5-5-15 (didn't have access to 18 on my mobo), and I've increased the v to ram to 2.0 (from default 1.8).

Still the computer reverts to disabling all overclock settings and I'm left with default.

Lowering my expectations a bit I've had fsb to 350 with ratio 1:1 and for some reason CPUZ reports 287 (or so) fsb and dram at 287. So bios 'forces' these settings somehow. So I get a decent overclock on CPU but it 'feels' as if I'm limiting my dram to 287 when it could run up to 333 (so far).

According to this review, even this mobo with an older chipset reached 350fsb:
http://www.hardcoreware.net/reviews/review-341-11.htm

Crashman, from this page it seems I could run memory up to ddr 888 (444?) with different multiplier setttings:

<i>Also note that the 945P does not officially support a DDR2-800 memory multiplier. Gigabyte have sort of gotten around this by adding a 2.66x multiplier which gives DDR2-709 speed (when the FSB is set to normal) and 3.33x which gives DDR2-888. So you have the choice of either underclocking or overclocking your memory. It's not the most elegant solution, but hey, AMD does the same thing with their AM2 processors ;) </i>

Page here:
http://www.hardcoreware.net/reviews/review-341-2.htm

Both, I'm not sure I understand that since mem is running dual channel and fsb is running approx 310 why I wouldn't need more - even with dual channel.

Why would a faster cpu and lower mem freq be faster than fast cpu and higher mem frequency?

Let's say fsb is at 310 with 1:1/2.0 ratios, so cpu clock is 3710 and dram is at 310 x dual channel it's 620. Why wouldn't I need more bandwidth to use more of that 3710 cpu clock?

Am I being thick? Maybe I'm missing something??
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August 8, 2009 10:19:00 AM

hanybanoub said:
Both, I'm not sure I understand that since mem is running dual channel and fsb is running approx 310 why I wouldn't need more - even with dual channel.

Why would a faster cpu and lower mem freq be faster than fast cpu and higher mem frequency?

Let's say fsb is at 310 with 1:1/2.0 ratios, so cpu clock is 3710 and dram is at 310 x dual channel it's 620. Why wouldn't I need more bandwidth to use more of that 3710 cpu clock?

Am I being thick? Maybe I'm missing something??


Why WOULD you need the half of your FSB that runs between the Northbridge and RAM to have a higher data rate than the half of your FSB that runs between the CPU and Northbridge? Why WOULDN'T you want them to run at the same speed (310 MHz)?
August 8, 2009 10:27:22 AM

thanks Crashman. So you're saying that fsb and ram should run 1 to 1 - matching each other for optimal performance?

During various attempts, I set fsb to 333 with ratios 1:1 but it's funny cause CPUZ shows 287 fsb and memory at 287. It appears that bios shows 333 but cpuz shows 287.

Can the bios 'force' settings that it sees as max or safe?
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August 8, 2009 10:35:05 AM

hanybanoub said:
thanks Crashman. So you're saying that fsb and ram should run 1 to 1 - matching each other for optimal performance?

During various attempts, I set fsb to 333 with ratios 1:1 but it's funny cause CPUZ shows 287 fsb and memory at 287. It appears that bios shows 333 but cpuz shows 287.

Can the bios 'force' settings that it sees as max or safe?


What you're probably not seeing is the change in "bootstrap" that takes place when you set various ratios. The motherboard might be setting things "wrong" when you choose an "invalid" combination of memory ratio and FSB clock.

It's a very old board, most people probably think you have a P45 rather than P945 chipset.
August 8, 2009 10:43:53 AM

Thanks again crashman :) 

what do you advise me to do with what I have my friend?

At the moment bus is running at 250, cpu clock at 3 ghz. Dram is running at freq of 333mhz with 3:4 ratios.

Is this optimal?

Or should I set cpu to approx 3.4 ghz and 280 mem freq?
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August 8, 2009 11:13:25 AM

If you're looking for best performance, CPU frequency is far more important than memory data rate.
August 8, 2009 11:20:06 AM

Thanks again Crashman. I think I understand lol :) 

cheers mate!
August 9, 2009 11:01:38 AM

Final question - I have DDR2 800 memory. A good bus speed I can get is 275.

However I am forced to set memory divider to 1:1/2.0. So my memory is running at 275 x 2 = 550.

As you can see it's a far cry from its 800 speed.

I've tried all sorts of divider settings but none work - sometimes it doesn't post, with other settings it posts but then windows hangs.

It seems that I cannot get higher bus speeds without sacrificing the divider and running memory lower.

What could be causing this?
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August 9, 2009 11:12:24 AM

hanybanoub said:
Final question - I have DDR2 800 memory. A good bus speed I can get is 275.

However I am forced to set memory divider to 1:1/2.0. So my memory is running at 275 x 2 = 550.

As you can see it's a far cry from its 800 speed.

I've tried all sorts of divider settings but none work - sometimes it doesn't post, with other settings it posts but then windows hangs.

It seems that I cannot get higher bus speeds without sacrificing the divider and running memory lower.

What could be causing this?


Some ratios don't work with some bus speeds. You could try using the one where "Windows hangs" by increasing DIMM and Northbridge voltage slightly.
August 9, 2009 11:15:33 AM

Thanks my friend I'll try it.
August 9, 2009 12:41:02 PM

Ok I've increased voltage to fsb, northbridge and memory by 0.1 for each.

I set the bios to 333 bus speed, multiplier at 2.0. I've booted in windows and typing this now.

however, cpuz is reporting bus at 279.3 and memory at same so 558 effective.

How could this be? Could bios bootstrap be the cause of the conflict? Is there anything i could do about it?

My main issue is my supposed pc-6400 ram is supposed to run up to 800. But I can never achieve bus speed that comes close to that.

Max bus speed has always been reported in cpuz id at around 278 or so, regardless of what I set bios.

Of course this affects memory speed and hence the source of all my questions: never achieving anything close to 800

What am I doing wrong my friend?

Sorry for going on about this but it's not logical.
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August 9, 2009 7:28:02 PM

Why should your system hit 400MHz just because your ram is rated that fast? By that logic you should get the fastest DDR2 out there and that should be your new fastest FSB. Just because your ram can go that fast doesn't mean the rest of your system can. What did I say in my first reply? Did you even read it?

Quote:
I'm not sure you hit 400MHz FSB with a 945 chipset. Thats probably much to much for that chipset. If you had a good 975/965 or the P35 it would be doable.


Your 945 is whats holding you back. You would know this if you did what I said to do. If you didn't read what I said, I doubt you did what I told you to do.
August 10, 2009 8:18:46 AM

4745454b said:
Why should your system hit 400MHz just because your ram is rated that fast? By that logic you should get the fastest DDR2 out there and that should be your new fastest FSB. Just because your ram can go that fast doesn't mean the rest of your system can. What did I say in my first reply? Did you even read it?

Quote:
I'm not sure you hit 400MHz FSB with a 945 chipset. Thats probably much to much for that chipset. If you had a good 975/965 or the P35 it would be doable.


Your 945 is whats holding you back. You would know this if you did what I said to do. If you didn't read what I said, I doubt you did what I told you to do.


Thanks for your reply.
!