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BIOS question

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  • Homebuilt
  • Memory
  • Systems
Last response: in Systems
September 9, 2006 4:36:25 PM

This has probably been answered dozens of times but I am not finding an exact answer so here I go :) 

Given the following MOBO, CPU and Memory:
MOBO: P5B Deluxe/WiFi-AP
vDIMM - This motherboard gives you 13-step voltage control to the DIMM.
vCore - Fine-tune it with 0.00625 volts at a time!
SFS (Stepless Frequency Selection) allows
- FSB tuning from 100MHz up to 650MHz at 1MHz increment
- Memory tuning from 533MHz up to 1066MHz at 1MHz increment
- PCI Express frequency tuning from 100MHz up to 150MHz at 1MHz increment

CPU: E6700
RAM: PC2 8500 (1066Mhz) or PC2 6400 (DDR2 800) (good quality in either case)
Vid: 7900gtx or 1900xtx (any high end pci express card).

Can someone tell me the optimal (for scenario with 1066 ram and 800 ram seperately).

1) FSB frequency?
2) Memory frequency/voltage?
3) PCI Express frequency?

The only reason I am considering the PC8500 (1066 mhz) ram is so I can get a 1:1 ratio between fsb and memory (thats optimal right?)
However, I am torn between the higher frequency and the CAS timing. PC 8500 has a rather high CAS it seems. Is the frequency more importaint or is the CAS? Or is there some magic formula to choose?

I checked the Cor2Duo OC guide (I am not interested OCing right away, I just want an "optimal" / "Standard" setting (I'll use a decent aftermarket air cpu cooler)....
However, the guide doesnt mention the E6700.... should I assume its identical to the E6600?
http://forumz.tomshardware.com/hardware/Core2Duo-Overcl...

thanks!

More about : bios question

September 9, 2006 5:15:19 PM

OK maybe I can help you out a bit. First off your core 2 FSB is quad-pumped so your actually running at a 266Mhz FSB, not 1066. Your RAM is DDR2 which is double data rate, meaning that DDR2 800 is actually running at 400Mhz and DDR 1066 is running at 533Mhz. So at stock frenquencies that only way to run a 1:1 ratio is with DDR2 533(which runs at 266Mhz). Of course many people run faster RAM and after DDR2 667, the extra speed makes up for the ratio loss. I would say that optimal in your case would be to download the latest Asus bios which enables the setting of lower cpu multipliers and lower your multiplier until you can set your FSB to 400Mhz and still get a stable clock speed, then run it with the DDR2 800 for a 1:1 ratio. Also for the PCI Express frenquency, I would lock it at 100Mhz. That's my plan anyhow.
September 9, 2006 5:33:34 PM

I think I get it...

I guess I am not excited about lowering the fsb to 400 (actually running @ 200), but maybe thats just me thinking bigger is alway better :) 

If
fsb of 200mhz x 4 = 800 (to match the DDR 800) gives me 1:1 ratio

then wouldnt
fsb of 266mhx x 4 (stock) = 1066 (to match the DDR 1066) to give me a 1:1 ratio.

Looks like the DDR 1066 is a perfect match to C2D. Am I not "getting it"?
Related resources
September 9, 2006 5:43:59 PM

Oh wait.. your saying I need to get the frequencies matching BEFORE double or quad pumping is in the equation?


So we are looking at for C2D x DDR2 1066

FSB RAM
266 533

To get a 1:1 ratio I would need to bring the FSB up and/or the RAM down to a matching frequency somehow. Then apply the double/quad pump multiplier and see what I end up with?

So out of the box I am looking at a 2:1 ratio with this memory / fsb / cpu combo. You think thats a loss when compared to using the ddr 800 and adjusting the frequency for the 1:1 ratio?

Thanks again!@
September 9, 2006 5:46:51 PM

Quote:
...
However, I am torn between the higher frequency and the CAS timing. PC 8500 has a rather high CAS it seems. Is the frequency more importaint or is the CAS? Or is there some magic formula to choose?...

They are both important, with no magic formula. A published benchmarking article indicates that latency clock cycles make the biggest difference when running at DDR2-667, but even there it was on the order of 2-3% in overall performance. Thus, I'd just get some good quality DDR2-800, even if you have to get CL5. (the Ballistix DDR2-800 CL4 2GB kit seems like a good deal right now at about $200 after rebate).
The memory voltage you'll need depends on the modules you buy. The rated timings should indicate which voltage was used, and you may have to go up to that voltage to get error-free RAM operation at those timings. However, it's best to start at 1.9V, a notch up from standard, and thoroughly test your system w/memtest86+ for at least a few hours. Once you get to a seemingly stable voltage, run the memory test O/N just to make sure.
September 9, 2006 5:50:16 PM

The Intel FSB is quad-pumped, meaning that your 1066FSB is actually running at 266Mhz x 4 = 1066. Your DDR2 stands for double-data rate meaning that DDR2 533Mhz is actually running at 266Mhz x 2 = 533. This would give you a 1:1 ratio as both the RAM and cpu FSB would be truly running at 266Mhz. When I mentioned running your FSB at 400Mhz, I was meaning that it would be 400 x 4 = 1600Mhz FSB. This would allow a 1:1 ratio with DDR2 800 since both the cpu FSB and RAM would truly be running at 400Mhz. This is great and all, but your cpu has what is called a multiplier and each cpu's is different. The multiplier is how you arive at your clock speed(multiplier x true FSB = clock speed). Your 6700 has a 10x multiplier which means if you left your multiplier at stock and ran your FSB at 1600(400x4) you would be OC your cpu to 4Ghz.(10 x 400) Since you probably don't want to do that, that's why I suggested getting the new Asus bios to enable the lowering of your multplier. This way you could set your multiplier to 6(6 x 400 = 2.4Ghz clock speed) or 7(7 x 400 = 2.8Ghz clock speed) and still run a 1:1 ratio with your DDR2 800 without having to OC the hell out of your cpu.
September 9, 2006 5:53:42 PM

Quote:
...
So we are looking at for C2D x DDR2 1066

FSB RAM
266 533

To get a 1:1 ratio I would need to bring the FSB up and/or the RAM down to a matching frequency somehow.

yes
...
Quote:

So out of the box I am looking at a 2:1 ratio with this memory / fsb / cpu combo. You think thats a loss when compared to using the ddr 800 and adjusting the frequency for the 1:1 ratio?

Nobody knows, or at least nobody has done the proper comparison and published it yet. The highest published comparison so far is to DDR2-800. If you get DDR2-1066 RAM, you can always run it at DDR2-800 if you want; OTOH, DDR2-1066 is pretty expensive!
September 9, 2006 5:55:24 PM

Ooohhhhhh Rainbow! I get it now. *bonk*

Thanks for taking the time to explain it to me ;) 

Cheers!

Preecher