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+12v wattage?

post #1 of 18
Thread Starter 
Hi guys, long time lurker first time poster. One of the best sites that i browse through from time to time and i have picked up quite a bit from here.

Was looking to upgrade to the following budget system mainly for gaming:

CPU: Athlon2 x3/x4, Phenom2 955BE

Mobo: 785g/sb710 Gigabyte( GA-MA785GMT-UD2H / GA-880GM-UD2H ) Asus( M4A88T-M LE )
760/sb710 Gigabyte( GA-MA78LMT-S2 ) Asus( M4A78LT-M LE / M4A78LT-M )

RAM: Kingston/Corsair 4gb ddr3

GPU: Sapphire/MSI 6850 (maybe the cyclone edition) or Sapphire 5850

Anyways my query is regarding my current PSU. Its a local brand called VIP 500. Below are the specs (i apologize for not being able to put up a picture of the label on the side as the camera on my cellphone is screwed..was garbage to begin with)


+3.3v +5v ! +12v ! -12v ! +5vsb

24a 30a ! 18a+18a ! 0.5a ! 2a

150w ! 216w+216w ! 6w ! 10w

484w

Total 500 max


First of all i just want to understand what exactly is going on on my +12v rails. Simple maths works out as 18+18=36 and 36*12=432W or am i horribly wrong (not the actual math ) here? How much is that thing truly putting out? Are they dual rails or just a gimmick? Is it providing enough for a 6850 to run on stock? Used to run a Gigabyte 8800GT on it a few months back without any issues. I also don't have a lot of fans and its just the single 1TB HDD in my case.

Now i do realize that's its nowhere in the league of brands like Corsair but our local vendors seem to suggest it over the equivalent CoolerMaster PSU's though i really can't infer why. I also understand the safest thing to do is get a branded one and be done with it but if this unit can hold out for at least 6 months, it will be the difference between getting the Phenom instead of the Athlon. Can't put of the upgrade as i am free for a couple of months now and might not be in a while. Really stretched thin budget wise and i am afraid if i have to get a new PSU then i can't afford the Phenom - might have to compromise with the mobo too.

Would really appreciate it if the wise folks over here could enlighten me on the workings of my +12v rail. Any suggestions regarding the processor and mobo are welcome as well.

Thanks in advance
post #2 of 18


This one?
Im looking at the review now, but yes, in technicality your 12v Wattage calculations are correct.
    
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post #3 of 18
It doesn't work that way..

You can't just combine Amps on rails to get total 12V+ amperage..

It must be specified by manufacturer what is total power of 12V+ rail..

For example I have Cooler Master Real Power M620W which has three rails rated @ 19A each..

Now by your logic total combined power on 12V+ rail would be 19+19+19 = 57A right???

WRONG!!!

Cooler Master states that combined power on 12V+ rail is 43A for this PSU..


So conclusion: Combined power of 12V+ rail must be specified by manufacturer.

It's only way for you to be sure..


CHEERS..
     
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post #4 of 18
The math is correct, however it is usually not applicable. When you have multiple +12V rails, you cannot add them together to obtain a combined wattage. The per-rail ampere ratings indicate how the OCP trip points are calibrated and not the maximum output available. See the label on the Antec TP-750: http://images.hardwarezone.com/uploa...89eea6f4f3.jpg -- you can make out 4 +12V rails rated at 25A, which would theoretically add up to 100A, making it a 1200W unit. Obviously that's not the case -- and it says under the table on the sticker that the max combined output is 62A. Any PSU that has multiple +12V rails and has an honest label should have a similar indication of the unit's actual output capabilities.

So in your case, while you may have two +12V rails with OCP trip points rated at 18A, while 36A@12V = 432W, you may not have that much wattage at your disposal, and the PSU should mention it.
post #5 of 18
^^^ What Shub said

It's probably more like 24-26A total on the 12V circuit, if history is any guide.

You can always try it, see if it works. If the PSU isn't adequate, it *should* just shut off w/o incident when put under too much load. Although if it's a real crappy unit, it could conceivably 'blow up' and damage other components.

Are you able to read the UL number on that unit? It should be 7 characters, starting with an "e" ... it'll be right under the logo that looks like a backwards "R" and "U".

If you can post it, this code will (usually) allow us to determine the OEM (actual maker) of the unit, which will in turn help us decide whether or not it's worth 'chancing it' with trying this PSU and the gear you've specified.

In any case I wouldn't risk overvolting any components (gpu or cpu) when using that PSU, and would be careful about overclocking, even running stock voltages on your components.
    
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xeon X5675 6-core @ 4.1ghz (1.29v, 20x205 +ht ) rampage iii extreme msi rx470 gaming X (the $159 budget king) 3 x 2gb corsair xms3 pc12800 (9-9-9-24-1T@1600MHz) 
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post #6 of 18
Thread Starter 
Thanx for the replies guys

Yes Mr Krogoth that's my PSU.

brettjv though i have never had a look at the number you have mentioned i will surely do it as soon as i get home and post it here so you guys can tell me if i can chance it or not.

So 24-26A is not enough in your opinion even though its dual rails?

Also how can i determine if my PSU has something like OPP?
Edited by Nihilanth - 6/13/11 at 12:00pm
post #7 of 18
I'm inclined to say that's probably a crappy PSU but there's no way of telling without at least opening it up and taking a look at the insides.
Since you're saying you were running a 8800 GT fine for a long time, and because the Radeon 6850 has roughly the same power draw as a 8800 GT, I'd say that wouldn't be a problem.
I might also suggest you look at a Core i3 2100 over a Phenom II X4, even though it has two less cores, it still beats the Phenom in most situations. The cost should be about the same.
post #8 of 18
Thread Starter 
Quote:
Originally Posted by brettjv View Post
^^^ What Shub said

It's probably more like 24-26A total on the 12V circuit, if history is any guide.

You can always try it, see if it works. If the PSU isn't adequate, it *should* just shut off w/o incident when put under too much load. Although if it's a real crappy unit, it could conceivably 'blow up' and damage other components.

Are you able to read the UL number on that unit? It should be 7 characters, starting with an "e" ... it'll be right under the logo that looks like a backwards "R" and "U".

If you can post it, this code will (usually) allow us to determine the OEM (actual maker) of the unit, which will in turn help us decide whether or not it's worth 'chancing it' with trying this PSU and the gear you've specified.

In any case I wouldn't risk overvolting any components (gpu or cpu) when using that PSU, and would be careful about overclocking, even running stock voltages on your components.
Ok just got back home and pulled the unit out. I am afraid i couldn't find the logo with R and U. Got a number though - 1138461 under ce cb fc sign. Any use? Found the box it came with - nothing on it either but went through the features and it lists short circuit protection, 100% burn-in test/vibration, Test/Hi-pot test/leakage. Is that good enough to prevent a barbeque of my proposed rig in case like you said i give it a shot before getting a new one?

Quote:
Originally Posted by Shub View Post
I'm inclined to say that's probably a crappy PSU but there's no way of telling without at least opening it up and taking a look at the insides.
Since you're saying you were running a 8800 GT fine for a long time, and because the Radeon 6850 has roughly the same power draw as a 8800 GT, I'd say that wouldn't be a problem.
I might also suggest you look at a Core i3 2100 over a Phenom II X4, even though it has two less cores, it still beats the Phenom in most situations. The cost should be about the same.
Ok didn't know that but what's the scenario in games like GTA4 and BFBC2? I mean isn't it safer to go with a quad now or am i mistaken?
post #9 of 18
Quote:
Originally Posted by Nihilanth View Post
Ok just got back home and pulled the unit out. I am afraid i couldn't find the logo with R and U. Got a number though - 1138461 under ce cb fc sign. Any use? Found the box it came with - nothing on it either but went through the features and it lists short circuit protection, 100% burn-in test/vibration, Test/Hi-pot test/leakage. Is that good enough to prevent a barbeque of my proposed rig in case like you said i give it a shot before getting a new one?
Sadly just because it's on the label doesn't mean it actually passes any sort of certification. They print all sorts of fun stuff on those labels, but they often lie

Quote:
Ok didn't know that but what's the scenario in games like GTA4 and BFBC2? I mean isn't it safer to go with a quad now or am i mistaken?
Yeah, I guess I can't tell you how well it performs with games that really do take advantage of quad cores. You should research it or ask on the Intel forums.
post #10 of 18
Thread Starter 
Quote:
Originally Posted by Shub View Post
Sadly just because it's on the label doesn't mean it actually passes any sort of certification. They print all sorts of fun stuff on those labels, but they often lie
Your probably right but how much would you say 30+ amps on a single rail equate to on a dual rail? Can't quite figure out how 36 A(combined) on dual rails comes upto 24-26 A overall. Is there absolutely no hope of running my intended purchases even on stock? I admit i am a real noob when it comes to PSU's



Quote:
Originally Posted by Shub View Post
Yeah, I guess I can't tell you how well it performs with games that really do take advantage of quad cores. You should research it or ask on the Intel forums.
will do
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