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Power Supply and amperes

P

PAPADOC

Member
I am overclocking my Q6600 and have hit a wall staying stable at 4Ghz.

The voltage I'm feeding it is 1.744


I can run stable at 3.6Ghz , but anything over that, the system will boot into windows up to 4Ghz, but any attempt to run Prime95 the pc restarts automatically closer to the 3.8 - 4.0Ghz range and produces errors closer to the 3.65 - 3.78Ghz range

I understand the heat may be a problem at 4Ghz, but at 3.645Ghz Prime95 should be ok I would think.


Now I am thinking the issue is with my PSU. I currently have the Antec Phantom 500, it has 2x 12v rails.
12v1 = 17amps
12v2 = 18amps --> for cpu
for a total of 35amps.

I know the cpu is using the 18amp rail to itself.
Now is it possible that the cpu is trying to pull in more than 18 amps when overclocked above 3.6Ghz , and since the rails are capped at 20amps the cpu isn't getting the amps it requires, hence causing the restarts?
 
It does appear that maby you are running out of 12v amps when it attempts to pull a full load. 18 amps is pretty low for an over clock like that.

Why are you running such a high voltage? That is not safe for the cpu and you're killing it's lifespan. 1.7 is way over the suggested safety range to have anything of a decent lifespan.
 
Yeah I know, I have to solder a potentionmeter to get it lower , but that's another story.

The strange thing is that I have a wattage meter connected to the pc's power cable, and the max amps that I saw on the meter was only 3.04 amps, does that make sense?

Is there any such thing as ac amps and dc amps?

 
Originally posted by: PAPADOC
The strange thing is that I have a wattage meter connected to the pc's power cable, and the max amps that I saw on the meter was only 3.04 amps, does that make sense?

Is there any such thing as ac amps and dc amps?
Click to expand...

You have to account for voltage. 3.04A at 120v is 364.8W. To put out that many Watts at 12v would require 30.4A.
 
Originally posted by: PAPADOC
The strange thing is that I have a wattage meter connected to the pc's power cable, and the max amps that I saw on the meter was only 3.04 amps, does that make sense?

Is there any such thing as ac amps and dc amps?
Click to expand...
Yes. It does make sense. The most important fact is that Watts = Volts x Amps (*). The mains voltage has a higher voltage, so the current will necessarily be lower.

(*) This is an oversimplification for AC circuits, but it's good enough for a simple explanation.
 
Originally posted by: PAPADOC
...

Now I am thinking the issue is with my PSU. I currently have the Antec Phantom 500, it has 2x 12v rails.
12v1 = 17amps
12v2 = 18amps --> for cpu
for a total of 35amps.

I know the cpu is using the 18amp rail to itself.
Now is it possible that the cpu is trying to pull in more than 18 amps when overclocked above 3.6Ghz , and since the rails are capped at 20amps the cpu isn't getting the amps it requires, hence causing the restarts?
Click to expand...

You don't add the amps across both rails to get a total amperage. You have to divide the total wattage across both rails by 12v to get the correct total amperage. A = W/V

I think a CPU would die before it could pull 18A all to itself.

Anyway.. this is why single +12v rails with huge Amerperage are advantageous over multiple rails as there is no loss due to the seperation of rails. It just keeps things simple.

The advantage over multiple rails is that it helps protect over components plugged into the other rails if one of the rails went "ka-blooie".

 
Originally posted by: tuksonrider
You don't add the amps across both rails to get a total amperage. You have to divide the total wattage across both rails by 12v to get the correct total amperage. A = W/V
Click to expand...
Many PSUs have 'fake' split rails which are not current-limited independently. Others are current limited independently, but can in fact output the combined sum of all advertised +12V rail current limits (e.g. "true" power ratings), though not on any single rail.

There is no easy way to know without A) opening the damned thing B) testing it to see whether each rail is output limited independently.

I think a CPU would die before it could pull 18A all to itself.
Click to expand...
I would have thought so, too, but not after checking the datasheet for Core2Quad and Extreme.

e.g. QX6850 @ 3.0GHz can hit 125A @ Vcc (~ 1.372V MAX), which is around 17A of 12V power after accounting for 20% VRM loss. This is a worst case scenario that is extremely unlikely in the wild but that is Intel's absolute rating.

He is attempting to hit 4.0GHz on his Q6600 using Vcc > 1.7V, which makes 18A or even 20A of 12V power seem plausible. Very stupid, but plausible (maximum safe Vcc is 1.55V).
 
If he can throw away 300$ on a q6600, he can spend 150$ for a decent powersupply. So let's suggest he gets a better, single rail PSU 😀
 
Originally posted by: Yellowbeard
Originally posted by: jmmtn4aj
1.7v?! 😱
Click to expand...

No, 1.744v and on air cooling too :Q
Click to expand...

If it was a 90 or 130nm processor that would make sense...really scary to put 1.744 into a 65nm core 2 quad. I don't see what the difference is between 4ghz and 3.6ghz besides a bigger e-p*nis. I'm sure nobody could tell the difference in a blind taste test. Imho, unless you're going after world records using extreme cooling, your ghz is really worthless to the outside world.
 
Originally posted by: tomoyo
I'm sure nobody could tell the difference in a blind taste test.
Click to expand...

Ummm, I think this one is the AS5, and the other one is Alumina. Wait, lemme lick that CPU again...
 
Originally posted by: Rocks7ar
Volts = Watts / Amperes
Watts = Volts x Amperes x Length
Amperes = Watts / Volts
Ohms = Volts / Amperes
Click to expand...

Ahhh....good ole Ohm's Law and the power formulas. High school flashbacks.
 
Ok, I am back, it took a while but I finally bought myself a new PSU with a single 12V rail.

I got the Corsair TX750W PSU.

60A on the single +12V rail.

So i had to switch that and 4 new fans , which took a while so I did a quick overclock test to see what happens.

Hence I ran Prime95 on all 4 cores at 3.6Ghz (400x9) , for about 5 min , and no errors reported. My voltage in bios was at 1.58 V

I raised only the FSB to 410x9 for an FSB of : 3.69 Ghz, ran Prime95 on all 4 cores, and after about 5 seconds , you guessed it , my pc rebooted ARGGHHHHHH!!!


Any thoughts on what else may be causing the issue I am all ears.
Unless my mobo or CPU are somehow limited to 400 FSB.
 
Memory, heat, or burnout of the CPU... You may have damaged it with such high voltage... Talk to VirtualLarry, he tortures his processors too. E2160s at 3.2GHz and 1.6v...
 
Originally posted by: PAPADOC
Any thoughts on what else may be causing the issue I am all ears.
Unless my mobo or CPU are somehow limited to 400 FSB.
Click to expand...

How about... your CPU is maxed out?

I know that it breaks your heart to hear it, but I believe in tough love. 😛 Plenty of people can't even hit 3.6GHz stable on their Q6600 chips, and you're hoping for closer to 4GHz? You'd likely have better luck if you were to sell your Q6600 and get a Q9450 or Q9300 or some other 45nm chip.
 
I lol at people overclocking and complaining that they're not able to get a higher OC even with such and such high quality parts 😛
 
Ok, I raised the voltage back up to 1.744 V,
and cranked the FSB to 420 Mhz for a cpu speed of : 3.78 Ghz

I booted into Windows and launched Prime95 on all 4 cores, ran it , and wow to my surprise it did not reboot. I ran it for about 5min, with no errors, hence maybe i have something good here.

Now, I have 4 new fans in my P180 , 2 exhaust and 2 push-pull on the heatsink.
they are the Sylverstone FM121's and , I put them on MAX (sounds like a jet),
they are spinning at about 2300 rpm , but unfortunately the ambient temp. in my room is ridiculous high, hence my temps skyrocketed to about 85 degrees Celcius.

And that is just insane, hence i stopped it, cause i don't want to blow my cpu it took me a while to lap it and I want to keep it for now, so I guess I will have to do this in winter lol.
 
Honestly this whole topic makes me cry. Someone trying to push a cpu beyond it's actual overclocking limits and tweaking his power just for that. I get depressed thinking about the poor Q6600 getting toasted to death in air cooling at insane voltages. It's like sticking a little baby inside a hot car forever. Nobody should do that to their stuff! This is a public service message for people against cpu torment ;_; Let's institute laws against cpu abuse!
 
Originally posted by: PAPADOC
Ok, I raised the voltage back up to 1.744 V,
and cranked the FSB to 420 Mhz for a cpu speed of : 3.78 Ghz
Click to expand...

There you go. Now try it at 2 V and record the time until it dies.

Honestly, if you really want to use this cpu longer then a couple of days, don't pump more then 1,5V in it, especially with air cooling.

 
I want to sooooo much, but i probably won't, I don't want to lose the chip and I need to start packing to move anyways, so I guess I'll wait.
 
Originally posted by: tomoyo
Honestly this whole topic makes me cry. Someone trying to push a cpu beyond it's actual overclocking limits and tweaking his power just for that. I get depressed thinking about the poor Q6600 getting toasted to death in air cooling at insane voltages. It's like sticking a little baby inside a hot car forever. Nobody should do that to their stuff! This is a public service message for people against cpu torment ;_; Let's institute laws against cpu abuse!
Click to expand...

I agree with this notion.
 
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