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Memory not running at specified speed

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blackwaterstout

New Member
Joined
Oct 19, 2008
I'm used to build PC's all the time back in the day. But the last 5 years or so I've kind of been away from them and recently upgraded my system.

I bought a AMD Athlon 64 X2 5600+ Brisbane, 4GB of DDR2-800 Corsair XMS memory, and a Foxconn A7GM-S AM2+/AM2 AMD 780G motherboard.

The Foxconn board says it supports up to DDR2 1066.
The Corsair memory is DDR2 800 (PC2 6400) Cas Latency 5,Timing 5-5-5-18

I've installed everything as per instructions but I'm having some odd issues with my memory speed.

In my Bios I have it set up as follows:
Current DRAM Speed 800MHZ
CUrrent CPU Speed 2900MHZ
Current FSB/HTT 1000MHZ
Current CPU Multiplier 14.5

My problem is when I run Sandra at default clock speeds it shows the CPU running at 2900MHZ but the memory speed shows 724mhz. Shouldn't this be reading 800? Especially since it's set to that in Bios.

I started up the Fox One software that came with the motherboard that allows for soft overclocking and it also shows 724mhz. Consdering all three items(CPU,MEM, and Moboard) all support DDR2 800 should my mem be runing at it.

The interesting this is if I use the Fox One software to push teh memory up to 800 it also pushes my FSB up to 221mhz which in turn runs the CPU at 3200MHZ. The system is actually stable at that speed so far. But I think I should be able to run the processor at 2900 and the mem at 800 shouldn't I?

I do plan on overclocking to some degree but I'd like to get this straightened out before i start pushing everything.

Anyone know whats up with my system?
 
i think its because your FSB is at 1000 rather than 1066, it looks like your processor is underclocked, therefore your ram is underclocked. raise your fsb in the bios to 333x4=1066 and you should get your missing mhz
 
It's because of the AMD DDR2 Memory Divider being /7 for x14 or /8 for x14.5.
2900/8=362.5 (x2)=725Mhz ram. Just keep running where you are or drop your
multiplier to x14. You'll however then be running @2800 Mhz CPU but
800Mhz ram. (2800/7=400 (x2)=800Mhz ram)
If you're running 3200 stable at or near stock Vcore that's
great and it will not harm your CPU at all. My 5600 Windsor is very stable
@3220 Mhz.
This is, of course, if your ram is stable with the OC and you may have to drop
your htt multi to x4.
Base frequency =200Mhz, Stock htt multi is 5, 200x5= 1000, @221Mhz, htt x5=1105
It is usually best to keep htt frequency at or below 1000, therefore lowering
your htt multi to x4 @221=884. Some, but not all boards will be stable above 1000,
you can test for stability. There is virtually no drop in performance with htt @884 Mhz.
Good Luck, keep us posted.
 
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It's because of the AMD DDR2 Memory Divider being /7 for x14 or /8 for x14.5.
2900/8=362.5 (x2)=725Mhz ram. Just keep running where you are or drop your
multiplier to x14. You'll however then be running @2800 Mhz CPU but
800Mhz ram. (2800/7=400 (x2)=800Mhz ram)
If you're running 3200 stable at or near stock Vcore that's
great and it will not harm your CPU at all. My 5600 Windsor is very stable
@3220 Mhz.
This is, of course, if your ram is stable with the OC and you may have to drop
your htt multi to x4.
Base frequency =200Mhz, Stock htt multi is 5, 200x5= 1000, @221Mhz, htt x5=1105
It is usually best to keep htt frequency at or below 1000, therefore lowering
your htt multi to x4 @221=884. Some, but not all boards will be stable above 1000,
you can test for stability. There is virtually no drop in performance with htt @884 Mhz.
Good Luck, keep us posted.
Excellent information. A little daunting considering I've never really spent much time overclocking.

If I were to change the multiplier to 14 and up the FSB to around 215 that would put me around 3000mhz. Would that also keep my memmory at 800? What would this do to the HTT? I'm not real familiar with htt and what it does and how it's adjusted.
 
I'm not familiar with the Foxconn bios but there should be an option to change the htt multi in there. The available multi's are 1x - 5x. The htt is based on
your nominal bus speed which for AMD am2 boards is 200Mhz. At stock speeds
this will be 200Mhz x5 = 1000Mhz. If you raise your bus speed to 215Mhz,
you'll be running the htt at 215x5=1075Mhz. Your ram freq. will increase to
about 430Mhz or 430x2=860Mhz. ( using x14 multi.) The ram freq. is not tied to the htt it is
locked to the CPU speed via the multiplier (eg.x14 or x14.5). The choice of
multiplier will give you fixed dividers that control your ram freq. Here is a DDR2
ram table which should help you out.
http://www.xtremesystems.org/forums/showthread.php?t=105798
There aren't any half dividers so when you use multi. x14.5 it is rounded up to the
next highest multi/divider which is (multiplier 15) /8. Hope that's not too convoluted!
Edit; the htt is a data bus that works at it's own multiple of your base freq. so you
have three frequencies to consider when you OC; CPU, RAM, HTT.
Not including your PCI and PCIE buses for now.
#2edit;Your CPU multi is still 14.5 on the rounding but the divider value increases
as if you actually chose x15. Sorry for any confusion.
 
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No, all you have to do is lower your HTT multi to keep it at or under 1000Mhz.
Your board might even be stable with HTT over 1000 because it's an AM2+.
Gotta go to work, be back later. There is no reason that you can't OC,
successfully!!!
Edit: Found a review of your board, duh, now I remember that you can run higher Htt
speeds on your AM2+ board and my comments were referring only to an
AM2 board. You should be able to run stable at higher Htt freqs. than 1000Mhz.
http://www.digital-daily.com/motherboard/foxconn_a7gm_s
The basics of OC'ing an AMD 64 based system will still apply however.
http://www.ocforums.com/showthread.php?t=391768
http://www.ocforums.com/showthread.php?t=306418
These threads will give you the info that you need to OC your system.
 
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No, all you have to do is lower your HTT multi to keep it at or under 1000Mhz.
Your board might even be stable with HTT over 1000 because it's an AM2+.
Gotta go to work, be back later. There is no reason that you can't OC,
successfully!!!
Edit: Found a review of your board, duh, now I remember that you can run higher Htt
speeds on your AM2+ board and my comments were referring only to an
AM2 board. You should be able to run stable at higher Htt freqs. than 1000Mhz.
http://www.digital-daily.com/motherboard/foxconn_a7gm_s
The basics of OC'ing an AMD 64 based system will still apply however.
http://www.ocforums.com/showthread.php?t=391768
http://www.ocforums.com/showthread.php?t=306418
These threads will give you the info that you need to OC your system.

THanks a ton for the info Stebly. You are the man!
 
Stebly, you seem like you know what you're talking about.

I'm gonna look at my timings and speeds again tonight, but in the meanwhile, using CPUz, where do you see what speed your mem is running at? In the SPD tab. My mem speed shows as 667 in my POST??
 
Your actual ram speed is shown in the memory tab, the spd tab shows the timings programmed into your ram stick. Yes, your "NB" will run hotter as you increase your freq. and/or voltage.
 
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