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Better performance with better ram, or not?

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acrh2

Registered
Joined
Jun 2, 2004
I've put together a system like this:
CPU: A64 Venice 3800+ @ 2.8GHz (10.5x266) @ 1.65V
RAM: 4x512 Geil Ulta Platinum PC4000 @ 215MHz @ 5-5-9-2.5 @ 2.5V
Motherboard: Abit AN8 SLI @HTT speed 4x266

I was hoping to get 30s in Super_PI, but I am getting 32.
I think the ram is holding me back. It's sandra benchmark is 5150MB/s.
This piece of **** ram won't even do what's in its SPD (5-5-9-2.0 @ 233, 5-5-9-2.5 @ 250).
I can't run anything faster than 225MHz even at CAS 3.
Increasing the voltage above 2.5V results in 1000-2000 errors in memtest. I did get a result once where increasing the voltage to 2.8V seemed to stabilize the ram, but I can't reproduce it, and I have already spent over 6 hours trying to tweak the ram.

Here are the questions for all overclocking gurus:
1) My other options are @ 280x10 the ram would run @ 233MHz, or @ 9.5x295 the ram would run @ 254MHz. Would I see better results in super_pi benchmark at those speeds? With better ram timing settings? How much?

2) If the answer is yes, what ram should I get? Would it be 2x1GB for 1T command rate?

3) If money is not an issue, what are my options?
 
Super PI strives on high freq, so you will need something that will go high. With your Venice core I assume that you can hit 2.7GHz, then I would recommend some OCZ Platn Rev2 which seems to hit 300MHz almost on all of their sticks. So you could do 300x9 with 1:1 ratio which would give you around 30sec in SuperPI.
 
I apreciate the time you spent to answer, but you didn't seem to read what I wrote: 1) the chip can do 2.8, 2) I need 2G of ram, which pretty much excludes ram speeds above 270 or so.
 
acrh2 said:
I've put together a system like this:
CPU: A64 Venice 3800+ @ 2.8GHz (10.5x266) @ 1.65V
RAM: 4x512 Geil Ulta Platinum PC4000 @ 215MHz @ 5-5-9-2.5 @ 2.5V
Motherboard: Abit AN8 SLI @HTT speed 4x266

I was hoping to get 30s in Super_PI, but I am getting 32.
I think the ram is holding me back. It's sandra benchmark is 5150MB/s.
This piece of **** ram won't even do what's in its SPD (5-5-9-2.0 @ 233, 5-5-9-2.5 @ 250).
I can't run anything faster than 225MHz even at CAS 3.
Increasing the voltage above 2.5V results in 1000-2000 errors in memtest. I did get a result once where increasing the voltage to 2.8V seemed to stabilize the ram, but I can't reproduce it, and I have already spent over 6 hours trying to tweak the ram.

Here are the questions for all overclocking gurus:
1) My other options are @ 280x10 the ram would run @ 233MHz, or @ 9.5x295 the ram would run @ 254MHz. Would I see better results in super_pi benchmark at those speeds? With better ram timing settings? How much?

2) If the answer is yes, what ram should I get? Would it be 2x1GB for 1T command rate?

3) If money is not an issue, what are my options?
The answers are not as simple or as straight forward as you might like them to be. First off, stay away from .5 multi's. A64 systems do not run optimally on them. Next, if you run at 10x280 with a 5:6 divider, your ram will run at 215MHz. This is because you ram speed is not a simple 5/6 of 280 computation. See this link.
http://www.lclark.edu/~daniel/a64mem.htm
If you run 2x1 gigs of ram you will be able to run at 1t. The best overclocking 1 gig sticks are the crucial ballistix. Will they out clock four good sticks of OCZ tcc5? That depends on the sticks. If you get lucky with the OCZ you could conceivably run 1:1 at 280MHz at 2t. As for super pi times, I don't know why you are fixated on them, but they are effected by your ram and cpu speed as well as the timings. I get the same super pi 32m times running 9x283 with the ram running at 231MHz 2-3-3-6, as I do running 9x280 with the ram at 280MHz 3-4-4-8. So, maximizing your results is something of a crap shoot depenfing on the quality of the ram you get. I would rather have the 1t timings myself, but the choice is all yours. Good luck.
 
rseven said:
The answers are not as simple or as straight forward as you might like them to be. First off, stay away from .5 multi's. A64 systems do not run optimally on them. Next, if you run at 10x280 with a 5:6 divider, your ram will run at 215MHz. This is because you ram speed is not a simple 5/6 of 280 computation. See this link.
http://www.lclark.edu/~daniel/a64mem.htm


Is this true for only rev E cpu's? I run my FX-55 Claw at 295 with a 10 multi, but need to use the 5/6 divider. According to the calculator I am only at 226. cpuz shows my RAM at a speed of 245.9 though. Seems like the bandwidth tests are on par with the 245 instead of the 226. :confused:
 
Ri0 said:
Is this true for only rev E cpu's? I run my FX-55 Claw at 295 with a 10 multi, but need to use the 5/6 divider. According to the calculator I am only at 226. cpuz shows my RAM at a speed of 245.9 though. Seems like the bandwidth tests are on par with the 245 instead of the 226. :confused:
No, this should be true on any A64 cpu, Use Everest or Sisoft Sandra to varify your true ram speed.
 
That calaculator is broken, there are other calculators that give different results (different from this one, but they agree among themselves). But in essence,
ram speed = cpu speed / ceil(cpu multi/ram ratio)
ram speed = 280*10 / ceil(10/{5/6}) = 2800 / ceil(12) = 2800 / 12 = 233.33
 
I am sorry I referred you to a broken calculator. I will make a note of it. I hope this doen't mean I have to do math again! :)
 
acrh2 said:
That calaculator is broken, there are other calculators that give different results (different from this one, but they agree among themselves). But in essence,
ram speed = cpu speed / ceil(cpu multi/ram ratio)
ram speed = 280*10 / ceil(10/{5/6}) = 2800 / ceil(12) = 2800 / 12 = 233.33


Ahhh, this makes sense why it gave me such low numbers with 10 multi. I was confused! :)
 
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