added a 2nd PSU

Zardon

I had been noticing at 4ghz, that when benching in pcmark02 with CPUz open that my core volts were sometimes dipping from 1.7 to 1.62 this didnt appear to be causing too many issues but I was quite unhappy with this. I am currently using a globalwin sapphire 520w 19db PSU and its pretty hardass but with the watercooling unit, 3 IDE hard drives, 2 raptors, a 9800 XT, audidy 2, raid card and 4 case fans I felt maybe it was time to help the globalwin out a little.

I picked up a decent little quiet 350w PSU today and have made a connection between pin 13 and 14 on this 2nd PSU power connector so when I push the power button on this PSU it will turn on the watercooling and 2 of the hard drives. My load figures are rock solid now. this also has the added benefit I can turn on the watercooling before the main rig comes online so its flowing and after the main pc is turned off, I can let the water circulate for a little, to aid the CPU cooling to idle.

zerodamage

Have some pictures of your setup?

Judas

i'd also like to see how this is working...BTW.. i had been talking to a rather "well informed" sounding man who said using 2 PSU's can actually be very hazordous as most have the voltages controlled somewhat by the motherboard.. and you can get loop back problems and whatnot... fighting between the 2 psu's... you name it....

Zardon

the prophet of doom im going to nick you. yes that is correct judas, but the 2nd PSU ISNT connected to the motherboard ! it isnt even INSIDE the case. its outside the case, shorted via pins 13 and 14 and connected to the WC, and 2 of my 5 hard drives (now as well the 9800XT), leaving the main 520w PSU with everything else. I can turn this on and off via the main 0-1 power button on the 2nd PSU.

Necrosis

Odd because the Northwoods are supposed to "bow" a little under full load.

Zardon

yes ive read that, but mine was more like diving not bowing, from 1.725 to 1.65 or less at times, now its only dipping like 1.725 to 1.7 under load, so it has worked. I guess I should also look into the droop mod.

Sourcer_2002

Yea i know that my weak PSU is causeing my stablity problems.

Judas

350 watt psu and 10 80mm fans... plus a few drives and whatnot.. overclocking... lots of memory.... according to the psu calculator... i'm over my limit of350 watts that my current PSU is rated at by about 40+ .....and the major reason i can get a stable result of 3200+ using the multiplier jump... (no FSB increase)....

Zardon

10 x 80 mm fans???

BWX

I've run a dual PSU setup for about 6 months now. I just got an Antec true control 550 a few weeks ago so I could ditch the Dual PSU setup. Well, I run allot of fans, I run them as slow as I can, but there's allot of them, I only have one HD, one CD burner, and the rest of the system in my sig..

My rails are exactly at spec and do not fluctuate more the .008v from idle to load under prime95 while testing them with a multimeter. Basically they do not move..

But still when I OCed to 210 FSB with the mem at 2-2-2-5 @ 2.8v yesterday and got everything running good, I didn't have my side panel on which has an 80mm and a 92mm fan (one blowing on Video card, one blowing on CPU), and I didn't have my 92mm blowhole fan hooked up either..

So I hooked up my side panel, I hooked up my top blow hole fan and restarted- Guess what- no boot.

I had to hold insert to startup to default to get into the bios,then when I started working my way back up I only got to 205mhz with the mem at 2-2-2-5, and I still couldn't run prime95- upping the voltage to the 2.9v or upping chipset voltage did not help, in fact it made it worse...

Basically, the Antec can not handle the extra fans without causing instability. I can adjust the rails all day long, but I will not get the same results with all my fans hooked up.. Granted I don't have a fanbus for the two 92mm fans and they are loud and cranking away at full speed, and when I get a fanbus I will be running them at around 7 or 8 volts, maybe less- but the other four 80mm fans are all adjusted for slower operation and my 80mm CPU fan is running at about 2600 to 3000 rpm (has it's own adjustment).

So the deal is, the more fans I add, the slower my system will OC. My PSU is not faulty either, it is the most rock solid thing I've ever seen. After I hook up the second PSU this time I'm gonna have to be very careful though- I don't want to mess up the Antec. After I get done I'll have 900watts of power on tap - Some PSU's have minimum rating too, and if the rating isn't fulfilled, they can be damaged. I think I'm going to put a 3.3v and 5v load on the 2nd one just so it doesn't blow up.

I also want to look into what Judas was talking about, because I am pretty worried about that- it doesn't seem like there would be any problem because you never plug the PSU into the other one, and you never plug either PSU into itself, so how could that happen? But if any component is hooked up to the mobo, and the mobo is getting its' power from the other PSU, that's where the problems could start..
Last time I had all my fans, my lights, and my CDrw hooked up to the second PSU, I think this time to be safe I am only going to hook up the fans and light to the second PSU- The 550w PSU will have no problem powering the MoBo, video, and drives, especially if it doesn't have the extra five 80mm fans, two 92mm fans, and 3 cathode lights.. Actually I can't even run my lights with this 550w, it just won't OC that high with EVERYTHING hooked up, and sometimes it won't boot at all..

Zardon

I think what judas was referring to, is if you solder leads and attach both the PSUs together into the mobo and act as a single PSU, (there are some mods to this on the net), and ive done one before but I was never happy with the results, there are also some sync problems which would be minimised by two PSUS exactly the same. in my case I really wanted to move the 12v watercooling kit away from the main PSU as I felt with 5 hard drives, 3 opticals, the 9800 XT, case fans and everything else it was really having to pump out some serious watts. I could also hear the variable fan speeding up quite often as if it was struggling to keep itself cool. this was something id never noticed until I got the P4 and starting overclocking. the dips in core voltages as necrosis said are part of the P4 deal but my dips at 4 ghz were sometimes almost 0.1 from 1.7 to 1.6 etc which I thought was a little outside a healthy zone. this 350w PSU as I said ive hooked up via pins 13/14 put it on the case facing me so I dont forget to turn it on before the main rig (that would be nice forgetting to cool the CPU ). Also in case by accident one day I did this, I put the 9800 XT into the 2nd outside PSU, so ill immediately get a beep beep beep if its not getting power.

The rails are better, as for overclocking well im pretty maxxed out as is, I just wanted to let my main 520w globalwin have a little more headroom. a cheap option too and there wont be any issues with feedback, syncing between the PSUs as they arent attached together in anyway. Also I can now start the watercooling unit before turning on the main rig, this is a good thing.

Judas

well i was thinkg the same thing BWX... but the guy just kept mentioning frequency and whatnot... being that i was hearing this... i wasn't able to actually get all of it...to much.. to quick... that and i can't hear worth anything.....

studbagel9

If you include every fan in my system, I've got 9 x 80 mm, 1 x 120mm, a vantec hdd cooling fan, and a 40 mm northbridge cooler that I put on my mobo. Also, throw in two 120 inch cold cathodes. all that on my 400 watt PSU... no problems at all

Zardon

ive just explained it in the post above.

Judas

the only thing i can even think of being a problem is if one PSU blows and lets say it's hooked up to some device(s) that go to the mobo and into the other psu... that it could have kind of forced short... that feeds back.... killing the other psu and all the hardware.. but man... you'd have to have the worst luck in the world... and it'd probably be me....

Zardon

I give up.

Judas

sorry....

Logla

I know what you mean

Necrosis

You know what I'm surprised PSU manufactures haven't already thought to build a "secondary" PSU for OC'ers. It could be a 12 volt only setup so it wouldn't have to be as big as a regular supply. I bet with some creative thinking..maybe even some kind of 5 1/4 bay insert would work great. Maybe even give it some fanbus/temp. options too. It's something to think about but of course it would need a power cord snaked through the case.

Zardon

Ive thought the same thing myself.