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Help with OC'ing a Q6600 on a evga nforce 750i sli board

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December 7, 2011 3:11:27 AM

I bought a evga 750i to work with my existing CPU. I was told that I am probably having a bottleneck with the SLI due to the 2.4 ghz Q6600 and need to OC the CPU to 3.0 ghz. I've read the over clocking guide can't get the bios to accept new FSB or memory settings linked or unlinked.

I have corsair DDR2 dual channel PC 6400 ram. I may have to buy a new CPU fan/heatsink I'll cross that bridge when I see the temps. Mobo is in a Antec 300 case with 4 fans. Even putting the 2 exhaust fans on high creates no temp changes that I've seen. Computer does put out heat but still CPU (w/ stock fan) and GPUs under load run from 50 degrees to 61. Changing out the two 120 mm fans which are noisy blowing air in or adding a third might make some difference. When I was running a single GPU OC at 10 or 15 percent was steady 50 degrees on previous mobo.

My problem beside never OC'ing a CPU before is I can't seem to get the bios to take any new settings on the FSB or RAM after saving and rebooting. Plus I can't use the 333 formulae linked or unlinked. Bios minimum values are 400. I've gotten it to take actually show a 2.70 ghz after reboot under linked IIRC but was in a black hole state and wouldn't POST. Is my RAM the problem why I can't get a 3.0 ghz? I've set the FSB to 400 and ram to 1200 which doesn't even show a change upon reboot. Attempting linked mode the ratios are reversed than what is in the OC guide.

I could use some advice.
a c 82 à CPUs
a b K Overclocking
December 7, 2011 8:48:38 AM

i have an asus motherboard with 750i chipset. the key is to up the northbridge and HT voltages to 1.4v. You will also probably need to pump up the CPU vcore voltage also, as these boards suffer vdroop (meaning actual voltage under load drops) So i set my vcore to 1.36, but under load it drops to 1.26 but remains stable. Keep your ram running at or slightly lower than its rated speed, and manually set the timings if you know how. You should be able to reach well beyond 3ghz with good cooling and a bit more voltage. If you have a stock cooler, upgrade the cooler. a coolermaster hypertx3 will do a fine job to cool that cpu and doesnt cost much.
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December 7, 2011 8:52:28 PM

Update: I figured out the OC what had me confused was the FSB QRD which I figured out and understand now. The bios on the board was already updated to current all though Phoenix technologies apparently has a bios upgrade which I'm reluctant to pay for membership to download it. I read in another thread that some features were removed. The evga board also doesn't have the HT voltage and the SPP or was it MCP voltage control. I set the bore to 136 IIRC though I can turn the VDroop off to manual on this bios. I achieved 3.0 ghz with a 700 MHz Ram freq. posted and ran fine on temps until I started stress test which it then locked up. Going to try and buy a fan tonight.

At the moment if I take back the RAM there are no 1066 ddr2s local without looking online. Did a quic search and didn't find any online either. I think I'm going to keep the 64 bit Win7 and install it later when I get the board stable. I feel like I wasted my money, but I may borrow the money to buy an I5 and and board after Xmas from my fiancé or hopefully I'll use my tax return.

I can't remember if I set the voltage on the ram to spec or raised it to 1.925 or w/e the next step up was. The ram factory spec is 1.9 v for my corsair ram 5-5-6-18-2t manually spec.

From what I've seen most of the Q6600s posted were GO revision. Mine is earlier I think. I'll take pictures of system info and bios late tonight and post it.
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Related resources
a c 172 à CPUs
a c 197 K Overclocking
December 8, 2011 5:50:49 AM

This should be your first stop.
Core2 Overclocking Guide (generic guide based on an Asus motherboard)
http://www.tomshardware.co.uk/forum/259899-11-core-over...

For your motherboard (BIOS's tend to be different):
http://www.pcstats.com/articleview.cfm?articleid=2104&p...
Look at the second set of screen shots (the top one labeled FSB and Memory Config).

Set memory to Linked. Once you do that, you should see Memory speed drop to 533 MHz.

The FSB speed is 1066 MHz. That is really the stock FSB clock. Speed is 1/4 of that - 266 MHz. The nForce 600/700 BIOS is a little strange. You adjust the FSB clock, not the FSB freq.

The screen shot for the voltages show their maximum values. Do not go that high or you will fry something.

So. Leave your memory timing on Auto. Set memory to Linked. For 3.0 GHz, FSB speed is 333 MHz, FSB clock is 1333 MHz, and memory clock will be 667 MHz. For 3.3 GHz, FSB speed is 367 MHz, FSB clock is 1466 MHz, and memory clock will be 733 MHz.

These combinations will give you a 1:1 FSB:RAM ratio and generally the best stability. Running the RAM faster gives little extra performance in a Core2 system.

Jump straight to 3.0 GHz. You will be forever nudging the FSB freq up 5 or 10 MHz at a time. You should be able to reach 3.3 GHz. You may be able to reach 3.6 GHz depending on your individual CPU, cooler, and case..

On my eVGA 680i board, running the memory Linked gave me a fair amount of instability, so I ran Unlinked and manually entered memory settings to let me run 1:1.

Keep the CPU core voltage under 1.50 volts and your load temps under 70 C. Do not exceed 2.2 volts RAM voltage.

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December 15, 2011 8:42:29 PM

jsc said:
This should be your first stop.
Core2 Overclocking Guide (generic guide based on an Asus motherboard)
http://www.tomshardware.co.uk/forum/259899-11-core-over...

For your motherboard (BIOS's tend to be different):
http://www.pcstats.com/articleview.cfm?articleid=2104&p...
Look at the second set of screen shots (the top one labeled FSB and Memory Config).

Set memory to Linked. Once you do that, you should see Memory speed drop to 533 MHz.

The FSB speed is 1066 MHz. That is really the stock FSB clock. Speed is 1/4 of that - 266 MHz. The nForce 600/700 BIOS is a little strange. You adjust the FSB clock, not the FSB freq.

The screen shot for the voltages show their maximum values. Do not go that high or you will fry something.

So. Leave your memory timing on Auto. Set memory to Linked. For 3.0 GHz, FSB speed is 333 MHz, FSB clock is 1333 MHz, and memory clock will be 667 MHz. For 3.3 GHz, FSB speed is 367 MHz, FSB clock is 1466 MHz, and memory clock will be 733 MHz.

These combinations will give you a 1:1 FSB:RAM ratio and generally the best stability. Running the RAM faster gives little extra performance in a Core2 system.

Jump straight to 3.0 GHz. You will be forever nudging the FSB freq up 5 or 10 MHz at a time. You should be able to reach 3.3 GHz. You may be able to reach 3.6 GHz depending on your individual CPU, cooler, and case..

On my eVGA 680i board, running the memory Linked gave me a fair amount of instability, so I ran Unlinked and manually entered memory settings to let me run 1:1.

Keep the CPU core voltage under 1.50 volts and your load temps under 70 C. Do not exceed 2.2 volts RAM voltage.



Okay sorry for taking so long. Computer was down, and I've been really busy. At one point I couldn't figure out why I was getting BOOTMGR error after post. So I'd reinstall the OS even made an iso had trouble getting the iso to load never done it without Ghost before. Finally the last time I did alot of basic installs before rebooting, and after that I reformatted and made a restore point for every reboot. I was real careful on watching what I installed. Not entirely sure what I did, but I suspect it was the raid driver for the board that did it. System has been running for several days now with win 7 64 bit Home Premium. I've had a lot of bad luck since changing boards. I noticed that the only SATA drive I had left had quite a lot of hours on it and SMART was showing it as nearly to the break point. Just my luck Hard Drive prices went up 2 months ago. :(  CRT I've had for over 10 years finally died LMAO!!! Had HDTV LCD hooked up for 2 days. Just bought a Samsung SA350 at a good price with 2 ms response at a really good price.

I've tried linked and unlinked both at 3.0 and 3.2 ghz for a stable clock. I think I may have actually had the correct settings, but the HDD not booting kind of messed me up there. I'm going to try again with the same settings I used before. Just to show I don't have a lot of options I took pictures of the important pages to show what I have disabled.

Anyone has any insight into what I'm doing wrong please feel free to comment. I'm loading CPUID and pictures of my bios. I have to run now. If I need to load text dump of CPUID or Dxd I'll post them later tonight.






Have to run!
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a c 82 à CPUs
a b K Overclocking
December 17, 2011 9:57:34 PM

your Vcore voltage is way too low in that cpuz screenshot, its less than what it should be for running that cpu at stock clocks. Increase your vcore gradually in BIOS and check with cpuz or preferably hwmonitor so you can monitor temps at the same time. you want the cou core voltage to be at least 1.25 before you even think about OC'ing. Also, you willprobably have to set it higher in BIOS as these boards suffer vdroop, meaning the actual volts are less than the BIOS setting. Im having a bit of an issue getting mine to OC any further (also using 750i chipset), running into a problem getting the FSB higher and needing to pump lots of voltagge into the HT link, reading other forums others dont seem to have to do this.
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December 18, 2011 4:31:24 AM

Well I've encountered a few problems 2 of which stem from vdroop and whether to enter ram timings manually and leave the rest of the ram options on auto or leave it all on optimal. I've acheived a stable 3.0 ghz OC with vdroop on I think I was on 1.50 or slightly below with FSB on 1.25 or 1.375 I think is the two options above 1.20v. The other problem is the RAM I bought RAM because the guy I bought the mobo from has the highest ram supported listed as ddr2 800. Every version listed on EVGA's 750i website shows it supports ddr2 1066/1333. I don't even see any ddr2's that are 1333 only the DDR3's.

Anyways the ddr2 800 leaves me clocking if at 1:1 ratio 1333 FSB QDR and 1333 Ram. The other ratios linked give various Ram OC's. 1:1 and sync doesn't give the same results.

The other problem I've had with a stable 3.0 OC when I've found a good vcore setting it boots to the desktop, but running prime on all 4 cores is stable for a bit then locks up at around 62 degrees celsius on the cpu. I re-entered bios after shutting down and found with vdroop on it had changed everything to voltages way in the red. I haven't found a stable voltage with vdroop off.

I'm a bit ticked off at the seller he listed ddr2 800 as the max supported. I'd have bought 1066 ram if I'd known better. I've already sent a email to the seller. I'd have to look at my receipt I may still be able to take the ram back, but Will have to use my older ram in mixed pairs if they don't have any 1066 in stock. If I can't get my money back I'm out the money ARGH!

Seriously if I'd known it would be this much of a hassle I'd just have spent the extra money and bought an i5 board with intel 2500k cpu and been done with it.

I think the main problem with my board is the bios version that it came with. I think phoenix took out some options that were in previous bios versions. I'll post my ratios next time I reboot.
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