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Comp turns off under load

D

DangerIsGo

2[H]4U
Joined
Apr 16, 2005
Messages
3,000
Wow, my first post in this forum.....

Ok down to business, last night I just volt modded my 2nd card to 1.55v (7900GT) in SLI. My machine is in my sig. Before the comp was volt modded, everything ran fine under load. I did gaming, ran some 3dmark runs, etc.. After volt modding, I ran 3dmark05 last night and about 1/4 the way into everything, the comp just turned off. wtf? Turned it back on and ran it again. Same thing. Unplugged 4 HDD's that I have (the ones in RAID) and ran 3dmark05 and it didnt turn off (yet I had a display driver problem..prob from the OC) So is the turning off from too much load? Or is it another thing? Its the only thing I can think of that its drawing too much power and it shuts off. Is there a device that will tell you if its reaching its limits? Does anyone have that toms hardware PSU stress testing guide that I can venture to look at for a new PSU? Im looking for something that will power my rig well under load and have room for expansion (step up to 7900GTX, dual core, and maybe 2 more HDD's) I dont want overkill like an 850 or kW PSU. What about a gfx psu to power my gfx cards? Are they worth it or just get a nice good one? I just read, how is the Enermax Noisetaker or the Seasonic 600W ?
 
Do you have to reset your power suply as well?

I have the same problem but with 7900GTX SLI. If I stress it really hard (Chaos Theory @ 2560x1600 everything turned up) it'll shut off in 2 seconds :)

I have an Antec Phantom 500W with only 17A and 18A on the 12V rails.

Your TruePower2 has 19A on each 12V rail, but they (my videocard boxes) recommend at least 22A :)
 
No, the comp just turns off as if i pulled the power cable (which i obviuosly didnt :D ) the 7900GTX wants 22A on the 12v rails? but then again, I also have 5 HDD's and many other higher end components too. Mine just turns off about 1/3 the way through 3dmark, let alone gaming. The enermax has 22A on the 12v rails while the seasonic has 18A on the 12 rails. :(

I just read that the 7900GT requires a nice 20A on the 12v rails while the GTX requires 22A i believe. :(
 
Those 12v figures are combined recommended of 20 and 22. Not per rail. The Seasonic has 36amps combined and the Enermax has 36amps as well.
 
According to Newegg, the seasonic 600w PSU has

+12V1@18A, +12V2@18A

Doesnt that mean that each 12v rail carries 18A while the min for 79GT cards is 20 or 22 from eVGA? Mine carries 19 no?

So for arguements sake, lets say its not the amperage on the 12v rails, what could be causing my CPU to shut down when the cards are under heavy load? i though its gotta be the PSU.
 
DangerIsGo said:
According to Newegg, the season 600w PSU has

+12V1@18A, +12V2@18A

Doesnt that mean that each 12v rail carries 18A while the min for 79GT cards is 20 or 22 from eVGA? Mine carries 19 no?
Click to expand...

Those 12v figures are combined recommended of 20 and 22. Not per rail. The Seasonic has 36amps combined and the Enermax has 36amps as well.
 
DangerIsGo said:
So for arguements sake, lets say its not the amperage on the 12v rails, what could be causing my CPU to shut down when the cards are under heavy load? i though its gotta be the PSU.
Click to expand...

2 volt modded videocards, an overclocked processor...all on a DFI board. I can think of a lot of reasons. Start by doing your basic troubleshooting. Kill all the oc's etc.
 
Spectre said:
Those 12v figures are combined recommended of 20 and 22. Not per rail. The Seasonic has 36amps combined and the Enermax has 36amps as well.
Click to expand...

Still kinda new to this, what do you mean by "Those 12v figures are combined recommended of 20 and 22"? I get the second part (18+18 = 36)
 
Spectre said:
2 volt modded videocards, an overclocked processor...all on a DFI board. I can think of a lot of reasons. Start by doing your basic troubleshooting. Kill all the oc's etc.
Click to expand...

But what if its the drain on the PSU from the OCs that are causing this?
 
DangerIsGo said:
Still kinda new to this, what do you mean by "Those 12v figures are combined recommended of 20 and 22"? I get the second part (18+18 = 36)
Click to expand...

Ok.

18+18 only means 36 amps on the seasonic. The Enermax is 22+22=36 because the same rectifier feeds both 12v's on the Enermax and as such is capped at 432w/12v. Those figures quoted by the card manufacturers are a total 12v amperage of 20 amps or 22 amps. 36>20(22).
 
DangerIsGo said:
But what if its the drain on the PSU from the OCs that are causing this?
Click to expand...

As long as the PSU is working properly and is being cooled properly to eliminate excessive derating nothing would really be gained by going to either PSU you linked since the TPII 550 has 36amps combined as well. So if you are over drawing the ANtec on combined 12v you would most likely over draw the others......unless you are only overdrawing one rail (12v1) then the Enermax may help.
 
Ok, I did some testing and this is what happened. Actually its not much testing but I narrowed it down. I left my CPU OC as it was (since that has been stable for months so I know for sure that its not that) and went to my gfx cards. I kept them in SLI mode and went to stock (500/750) of the lowest card and fired up 3dmark05 and 06. No problems running either one. Went straight up to 725/750...turned off. Went down to 715, crash. 700, crash. 675, crash. Now @ 650 going for some time now (about 1/2 hour) and comp is still on. When a single card is enabled, i can keep it @ 725/1000 no problems under load but it seems when both are enabled at that speed, its not good. PSU?

As far as temps, they are well below good as im using a stasis on one block and maze4 on the other. Neither one breaks 45C under load. CPU doesnt break 40C either. But I do have to admit that when I put my hand behind the PSU that its awefully warm....warmer than my radiator sometimes. I think thats becuase of the poor efficiency no?
 
Can you increase the PSU fan speed by playing with the thermistor that controls it, such as by blobbing silicone rubber sealant between it and the heatsink and pressing it against the heatsink?
 
If you have a table fan or something those lines remove the side of your case and point it in there. Ideally getting cooler air through the PSU. If you don't have the air on and it's say 80-90F ambient in your room the power output of the PSU could start dropping fast.

A power supply could theoretically produce all the power you wanted as long as you kept it cold enough. So if you put a slab of dry ice next to it and start blowing air over that into the PSU you could put a serious load on it.
 
Anarchist4000 said:
A power supply could theoretically produce all the power you wanted as long as you kept it cold enough. So if you put a slab of dry ice next to it and start blowing air over that into the PSU you could put a serious load on it.
Click to expand...

LOL
 
DangerIsGo said:
Is that true? :confused:
Click to expand...
yep, the hotter a psu runs the less efficient it is.
i think this is what happened to my 600w noisetaker. the ambient temp in my room is usually pretty warm and i think continuous use in the heat finally blew it up.

i just ordered a coolmax ctg-1000 to remedy the problem...
 
DangerIsGo said:
What did you do?

As far as mine, theres a 120mm in there thats always running.
Click to expand...
this is what happened to mine. im still praying all my components are ok.

http://www.hardforum.com/showthread.php?t=1074393

i definitely have enough airflow but i think my system was just stressing the PSU just a tad too much...
12 120mm fans puts quite a load on top of everything else...
 
So what do you think i should do in this situation? It seems my heft OCs are draining this PSU. Its going to be even worse when I get GTXs after the step ups.
 
Haste266 said:
maybe i should of said get a "higher end psu" instead...
most(and notice i said "most") of the 650w+ units nowadays are "higher end". dangerisago seems to know his stuff, so...me being more specific was pointless.
Click to expand...

Higher end PSU's won't neccesarily net him anything much better than 36 amps combined on the 12v. If someone needs more than 36 amps (doubtful) they have to be very careful in their selection to get a unit that actual has more than that and has the neccesary rail configuration for their setup.
 
Im kinda learning about this (even though it IS part of my major :p) as I go along. Would a higher end one from lets say enermax which as 22A on the 12v rails help my situation? Isnt the higher amperage per rail a good thing? Im trying to decide what I can do about this and how to fix it...also what PSU to get (if it is the problem). Ill read that 'watts dont mean jack' thread now.
 
DangerIsGo said:
Im kinda learning about this (even though it IS part of my major :p) as I go along. Would a higher end one from lets say enermax which as 22A on the 12v rails help my situation? Isnt the higher amperage per rail a good thing? Im trying to decide what I can do about this and how to fix it...also what PSU to get (if it is the problem). Ill read that 'watts dont mean jack' thread now.
Click to expand...


It depends. Keeping in mind the 22 amps on each rail is not additive and the unit is capped at 36 amps total, if you are currently over drawing the 18 amps on just the 12v1 with both videocards the higher 22amp limit may indeed help.

Though the 7900GTX only draws about 6.75 amps stock.

http://www.xbitlabs.com/articles/other/display/fsp-vga-power_6.html
 
So just to confirm, what exactly IS a rail? Is it the line that gives out 12v to a device? or devices? 12v goes to my vid card but 12v also goes to my HDDs, live drive, etc.. And is more rails better? Like I see PSUs with 3 or 4 rails and some only have 2 or 1
 
DangerIsGo said:
So just to confirm, what exactly IS a rail? Is it the line that gives out 12v to a device? or devices?
Click to expand...

Yeah it is the name of the individual supplies of voltages 5v, 12v1, 12v2, 3.3v etc.

12v goes to my vid card but 12v also goes to my HDDs, live drive, etc..
Click to expand...

Correct on an ATX12v2.0 compliant PSU 12v2 feeds the processor alone through the P4/Aux connector and every other 12v device draws from 12v1.

And is more rails better? Like I see PSUs with 3 or 4 rails and some only have 2 or 1
Click to expand...

It really just depends on the application. A big fat single 12v is preferred soemtimes because you have more give because you won't overdraw a small 12v rail. OTOH multiple 12v rails isolate high draw components from one another to minimize rail fluctuation.
 
ok, i have a question now...
say you have a quad rail psu. how do you know the load is being balanced correctly between all the rails? is it a matter of seperating the load to different connectors as evenly as possible? or does the psu adjust for this automatically?
 
Yeah i was just gonna ask, is having a quad rail @ 15A each better than a dual rail PSU @ 22A each? And why do some higher end models (like PC power and coolings 510w, and some enermaxs) have less than 22 (or 20)A on the 12v rails?

I found this spectre, v1 is the CPu and v2 is everything else:

EPS12V ....6.1.1 12V Power Rail Configuration

There are two types of 12V rail configurations for systems: 'Common plane' and "Split plane' processor power delivery. The 'common plane' system has both processors powered from a single 12V rail (+12V1) from the power supply. The 'split plane' system has both processors powered by seperate 12V rails (+12V1 and +12V2) one dedicated to each processor. The system in both cases, has an additional 12V rail to power the rest of the baseboard +12V loads and dc/dc converters. +12V1, +12V2 and +12V3 should not be connected together on the baseboard to ensure that 240VA protection circuits in the power supply operate properly

Table 6: 12V Rail Summary
........................................................................................................................................................................................
Common Plane System........................................................Split Plane System
+12V1........Processors.........................................................+12V1........Processor 1
+12V2........Baseboard components other than processors.......+12V2........Processor 2
+12V3........Drives and peripherals..........................................+12V3........Baseboards and components other than processors
...........................................................................................+12V4........Drives and peripherals
Click to expand...
 
DangerIsGo said:
Yeah i was just gonna ask, is having a quad rail @ 15A each better than a dual rail PSU @ 22A each?
Click to expand...

Not neccesarily. You have to know how those rails are divided and what they are powering and what the combined output is.

And why do some higher end models (like PC power and coolings 510w, and some enermaxs) have less than 22 (or 20)A on the 12v rails?
Click to expand...

The PC Power and Cooling has a single 12v rated at 34amps (38 amps peak). And basically it is for the reason I stated earlier about big single 12v's.
 
Not neccesarily. You have to know how those rails are divided and what they are powering and what the combined output is.
Click to expand...

In my case, is the gfx cards drawing too much amerage from the rail? Would the seasonic or the enermax be preferred to fix that? Or another PSU? I really dont wanna get a PCPAC 510 cuase its too much money. What would you prefer with my rig? Im looking at the seasonic mentioned above, the enermax liberty 600w and the enermax noisetaker Remembering that Ill be upgrading to GTXs soon and then after that, dx10 cards (maybe quad SLI if I can afford it at the time :p and possibly another HDD or two.)
 
Im really looking at the enermax liberty 620w cuase of the high wattage, 22A rails, and the modular plugging. what do u guys think?
 
Ew, It says for me 532w but thats a stock 7900GT. I put it as a GTX (stock and OCed )and it gave me between 588 - 597w :(

I plugged in a secondary PSU to power just my HDDs and ran my cards OCed ...they are still under load and its been half hour. So its not a conflict w/ the HDDs and the gfx cards OC (not like that would happen) So its gotta be the PSU. :(
 
undertheradar said:
This might help you as well....
http://extreme.outervision.com/index.jsp
Click to expand...
It misses the exact problem of over drawing a single rail that we were talking about. That is the exact reasons why it is in big bold lettering in the how to buy sticky that it is NOT recommended. The creator says that he is working on one that will give amps per rail...until then though it is of no help.
 
Well, its of SOME help. I get what you are saying though...its more likely that he is overloading one rail due to a load imbalance than overloading the whole PSU. But its a tool of 'elimination' still. If he punches in the computer layout he has, and comes up with a PSU that is a couple hundred watts over what he has...then he might really need a larger PSU. If he punches in what he has and comes up with something with equal or less watts than what he has, then he is most likely overloading one rail.

The tool still has its purposes.
 
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