P4S533 CPU/Memory Ratio?

dajo

Senior member
Nov 7, 2000
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Hello,

I'm hoping that some of you P4S533 experts might be so kind as to take the time to answer some of the following questions. I would appreciate it. I've built many AMD systems, but this is my first Intel "home build" (I've supported many older Intel platforms at work, though).

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Currently, I have my CPU/memory ratio at 4:5 with a P4 2.4b (133MHz) processor and my FSB set to 156MHz. This effectively means I am running my RAM at 166+23=189MHz, right? Am I doing these calculations correctly?

Also, according to the FSB BIOS I'm running my PCI bus way out of spec but everything seems very stable. I've seen others using even higher FSBs so I am wondering how this board handles the PCI bus at this rate. There doesn't seem to be a PCI divider in effect or the BIOS screen wouldn't (or shouldn't) show the PCI bus at 41MHz. Why is my rig still stable?

Also, it seems that 3.0GHz is the limit of this board for my processor (166 * 18x). Is that correct?

My SS mem score is 2824 with Corsair XMS 3200C2 running at 2-3-3-6-1 at 189MHz (if above calcs are correct) but I'm seeing others with similar setups scoring over 3000. Am I doing something wrong here?

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PS.
My chip seems to be a good one. I'm running at 2809MHz while still at default voltage and with CPU temp of 33C.
 

Tates

Elite Member
Super Moderator
Jun 25, 2000
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4:5 = 156/4*5=195*2=DDR390. You should be able to run your XMS3200C2 at 2/2/2/6/1 and your SySoft Sandra mem scores will rise.

At 156fsb, your AGP/PCI are running at 78MHz/39MHz. Since there is no AGP/PCI lock, you won't be able to push it any further.

Still, 156fsb is a nice oc on a P4S533. :)
 

dajo

Senior member
Nov 7, 2000
635
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Hmmm...

I thought it went more like this:

cpu/mem = 4/5; CPU bus is 133 so,

Formula: 4/5 = 133/x

133/x=4/5
1/x=(4/5)/133
x = 133/(4/5)
x = 166FSB

Is this math/logic correct?

I'm running at 156 through the CPU frequency and since the CPU runs at 18 * 133 by default I thought this meant that I was overclocking above the 166 async mem timing by a factor of 23 (156-133).

This would give a total of 166+23 = 189FSB.

Is this incorrect? I'm not trying to be stubborn. I'm just trying to understand how to calculate the actual RAM speed since the board is capable of running the RAM async with the CPU bus.

==========
Eh, whatever the case my rig is damn fast now and kicks the crap out of my former MSI KT3 Ultra with unlocked XP2200+. Very stable and robust platform, too.
 

dajo

Senior member
Nov 7, 2000
635
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I don't doubt that. I just don't understand

How do you set the board to run the RAM at 166? I thought the settings allowed for running the RAM at 133/166/200 through selection of the cpu/mem ratio?
 

Tates

Elite Member
Super Moderator
Jun 25, 2000
9,079
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Simple. There is no option to lock DDR at 100/133/166 and run the FSB of your choice. It is a function of the CPU/DDR ratio setting.

memory ratios available on the p4s533:

100>132 fsb
1:1 at 100fsb mem at 100
3:4 at 100fsb mem at 133
3:5 at 100fsb mem at 166
3:6 at 100fsb mem at 200

1:1 at 120fsb mem at 120
3:4 at 120fsb mem at 160
3:5 at 120fsb mem at 200
3:6 at 120fsb mem at 240

1:1 at 132fsb mem at 132
3:4 at 132fsb mem at 176
3:5 at 132fsb mem at 220
3:6 at 132fsb mem at 264

133>160 fsb
1:1 at 133fsb mem at 133
4:3 at 133fsb mem at 100
4:5 at 133fsb mem at 166
4:6 at 133fsb mem at 200

1:1 at 140fsb mem at 140
4:3 at 140fsb mem at 105
4:5 at 140fsb mem at 175
4:6 at 140fsb mem at 210

1:1 at 150fsb mem at 150
4:3 at 150fsb mem at 112.5
4:5 at 150fsb mem at 187.5
4:6 at 150fsb mem at 225

1:1 at 160fsb mem at 160
4:3 at 160fsb mem at 120
4:5 at 160fsb mem at 200
4:6 at 160fsb mem at 240

Above 160fsb you only have 1:1 and 4:3.

PCI dividers are automatic at 1/3 and 1/4.
1/3 to 132fsb
1/4 over 132fsb up to 166fsb

There is no 1/5 pci divider.
 

dajo

Senior member
Nov 7, 2000
635
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Thanks for all the info. I re-worked the formula based on actual setting of 156. Sorry, but I have to do this "by hand":

4/5=156/x
156/x=4/5
1/x=(4/5)/156
x=156/(4/5)
x=156/.8
x=195

So, I am currently running my RAM at 195FSB?

I tried 2-2-2-6-1 for the RAM but system wouldn't reboot and put me in the "you've overclocked too much" BIOS mode. Specs at 200 for this RAM are 2-3-3-6-1 which is what I'm running. On the other hand I haven't up'd the DDR voltage yet. Maybe I should give that a try.

Oh well, like I said, system is quite fast regardless of SoftSandra which I always take with a grain of salt anyway. Fun for benchmarking, but then the real test is using the machine.

Do you think a PC1066 platform is the way to go?

Since I'm already at 2.8GHz and still at default voltage for the processor it may do considerably more. Do you have any board recommendations which would provide a 1/5 PCI divider?

Thank you for spending so much time on my post.
 

Tates

Elite Member
Super Moderator
Jun 25, 2000
9,079
10
81
Yes, you are running your DDR at 195MHz fsb for an effective 390MHz (195*2). You might try 2/2/2/7/1.

Seems that DDR has as good, if not more of, a future as Rambus (PC1066), what with the Granite Bay chipset for Dual channel DDR on the horizon.

I'ld be extremely happy with 2.8GHz at default voltage.
 

dajo

Senior member
Nov 7, 2000
635
0
0
Thanks again for all the help and time you have given me.

I am extremely happy with 2.8GHz at default voltage and still can't quite believe it. System is nice and cool at 33C with AX-478 and an Enermax 80MM three speed fan set to lowest setting (I don't really like fan noise much).

Just curious about the Intel platforms as I don't know much about them. I've built many AMD systems over the past five years, but this is my first Intel build and I'm am very impressed.

See you in the forums!