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Overclocked Q6600 using "tape" mode - prime95 fails

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a b à CPUs
August 3, 2010 6:26:01 AM

well its been a while that ive had a G0 Q6600 at 3.0ghz using the tape mod which all it does is bump up the fsb to 333mhz so it goes from 2.4 to 3.0 ghz. Ive never had instability in any games or everyday usage, but when I run prime95 i fail pretty quickly (blue screen) like 2-5 mins and the temperatures are fine. Just now I blue screened at 65 degrees.

extra info:
this is a locked acer G33 motherboard so I had to use the tape mod to overclock
my ram is 4gb of 667 mhz ddr2 ram - this is running in a 1:1 ratio with the fsb of 333mhz
i think my v core is at 1.28 volts although i cant alter it in the bios at all
win7 64-bit

so any ideas on why I am failing prime95 , also should i care that I am failing it, everything else is fine, never had troubles with anything.
a c 100 à CPUs
a b K Overclocking
August 3, 2010 8:22:35 AM

I don't know what the tape mod is but have you tried lowering the memory multiplier?
a c 100 à CPUs
a b K Overclocking
August 3, 2010 8:26:52 AM

Have you tries lowering the RAM multiplier?
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a b à CPUs
August 3, 2010 3:21:15 PM

nope, how would I go about doing that? pretty much everything is locked on the bios
the only thing I can change is memory from 667 to 800 or to auto I have it at 667 because that is what is installed.

this is the tape mod: http://forums.nvidia.com/lofiversion/index.php?t58361.h...

it is exactly like bumping up the fsb from 266x9 (2.4ghz) --> 333x9 (3.0ghz)
a c 100 à CPUs
a b K Overclocking
August 3, 2010 5:19:49 PM

Theres the problem upping the FSB is also increasing the RAM speed by the same amount. Just to check if you run Prime 95 blend test it should crash alot quicker than small FFTs. If not its something else.
a b à CPUs
August 3, 2010 10:06:26 PM

thats what I thought initially but I checked my ram specs and they are still at 667mhz based on cpu-z and on my mobo i selected 667 as opposed to auto.
also the blend test crashes as fast as the small FFTs
thanks for the suggestion I dont think it is the ram speed tho I could be wrong.

Maybe it is bad ram in general? how would I check this?
maybe I should remove the mod and see if it becomes stable?

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a b à CPUs
a b K Overclocking
August 4, 2010 12:26:37 AM
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It might be a problem of to little voltage for to high a frequency. And without the ability to bump it up some I doubt there is anything you can do. <1.3v is not really enough for OCing the 65nm quads. I would say drop the multiplier to 6 to see if the system can handle the 333MHz FSB, but if the bios is locked and you can't then obviously thats not going to work.

The question then becomes (and good for you for asking) does this matter? Prime might fail and it becomes a "failed" OC, but if its stable in the programs you use then its not. Prime and anything else that needs a high CPU load will have issues, but if this is just a surfing/game playing machine then your fine. You might want to consider a new board. Buying one used for $50-75 might be worth it. It will allow you to reuse all your current stuff, while providing an unlocked bios and possibly more features.
a b à CPUs
August 4, 2010 3:40:52 AM

thanks for answer bro,
also one more question If I do switch my mobo, wouldnt I not be able to overclock any further than this because at 333mhz fsb arent I maxing out my 667mhz ddr2 memory's? Like if say I bump up the fsb to 400 mhz wont the ram have to be at least 800mhz to boot up?
a b à CPUs
a b K Overclocking
August 4, 2010 3:48:35 AM

Yes and no. First, you can try overclocking your ram. DDR2-667 isn't that far off DDR2-800 so if you have good ram (or relax the timings and overvolt a bit) you can probably hit DDR2-800. Second, while not ideal you can use a ratio to keep the ram at DDR2-677. It won't be as fast as it could be, but you'll still have a faster CPU.
a b à CPUs
August 4, 2010 4:45:16 AM

Best answer selected by amirp.
a b à CPUs
August 4, 2010 4:49:06 AM

thank you for the info bro, I might do that ... as an inexpensive upgrade for now
the q6600 overclocked to 3ghz+ is still a more than decent cpu to have right?
a b à CPUs
August 4, 2010 4:50:39 AM

and yea you are right the v core is probably too low,
what is the reason that more voltage is needed ? to provide more power to it right because since it is overclocked it needs more juice to run stable?
the downside to this is heat and inefficiency I presume?

Lol and according to your profile you joined 9 years before you were born... nice pro at computers even before conception.
a b à CPUs
a b K Overclocking
August 4, 2010 5:11:05 AM

All the profiles before X date are bugged. Not sure why toms hasn't fixed it although it doesn't really matter. More voltage is needed to get the transistors to switch on and off faster. The slower the speed you want them to switch, the less voltage you need. You can also use less voltage if the transistors are smaller. This is why the 45nm CPUs need less voltage then the 65nm ones. Yes, the downside would be heat. Inefficiency I guess. Higher voltage would increase the amount of power used there by effecting your performance per watt figures. If you get the performance up enough however it might be more efficient.
a b à CPUs
August 16, 2010 3:38:09 AM

4745454b said:
Second, while not ideal you can use a ratio to keep the ram at DDR2-677. It won't be as fast as it could be, but you'll still have a faster CPU.


When you say I can use a ratio to keep the ram at 667 (333mhz) what would an example of such a ratio be?
for example lets say i get to 400mhz fsb, and the ram is still at 333.
That would give a ratio of 400 : 333 which is 1.2 : 1 which is 6 : 5
am I completely wrong lol? I am just trying to understand this ratio stuff, and such a setting is available to any motherboard which is bought right?


another question I have is if i get the fsb to 400 mhz, would I need a motherboard that would support at least 1600mhz FSB right?

thanks, and sorry for my noob-ness
a b à CPUs
a b K Overclocking
August 16, 2010 5:31:09 AM

6:5 sounds about right. Every bios is different, so it might be marked differently. Some take all the fun out of it and just give you speeds. DDR2-667, DDR2-800, etc. No clue what your board uses.

No board will list 1600FSB. Pretty sure they can only list the official speeds so 1333 is probably the fastest you'll see. (not 100% sure about this.) Its pretty uncommon to find a board that can't do 1600 or better as long as you stay with mainstream chipsets. P41 probably can't, but just about every P45 should.
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