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View Full Version : So ive switched to the Light Side(Nvidia) 7800GS but need help


ReDxKiNG
03-26-06, 09:57 PM
So after 4 years with my trusty 9700pro I finally have found a card deemed worthy of an upgrade for my aging agp system(which i am very happy with by the way). I have absolutely no interest in pci-e and any of that other "hoopla" at the moment but that may change next year...Anyway back to the purpose of me making this thread. I am currently on a 3 year old 350watt power supply and immediately realized this would not be sufficient for the 7800gs (The overclocked BFG one in case you were wondering) so the first thing I did was go on tigerdirect and get a better power supply and I ended up getting this one http://www.aselabs.com/articles.php?id=85 (ThermalTake Silent PurePower 480W PSU ). I was soo excited about upgrading that i rushed to just grab the first psu that i thought was good, but I later found out that its not really about how many watts your psu has but more about how many a's your 12v rail has... Unfortunately I didnt realize this sooner because I had already placed the order without researching this issue/requirement first..Now my problem is that on the BFG site,they recommend A "minimum 400W system power supply (with 12V current rating of 20A or more)" My problem is that I have now found out that my PurePower 480W psu only has a 12v Rating of 18A :( and thus i am now worried that I just purchased a new psu like a fool and it will probably be useless in powering my 7800gs. Any advice? Can the 7800gs manage on a 18A 12v rail? Also can i get a refund from tigerdirect or at least an exchange or something if It doesnt work with my card? ( I bought both the psu and card from tigerdirect,simultaniously)Any advice,help or tip would be greatly appreciated, As i have always been an ATI guy (yes i know, ive been part of the dark side for way too long...) and im not really too familiar with nvidia.

keith33
03-26-06, 10:04 PM
What kind of CPU do you have? I had that power supply 2 years ago, it couldn't run my 6800 Ultra and my A64 2800+ stable at the time. If I were you, return it, bite the 10% bullet or whatever it is and get something that will last you an upgrade at least. Even if it somehow works, it'll be just barely.

ReDxKiNG
03-26-06, 10:09 PM
Im on a Pentium 4 2.4ghz 533fsb

MustangSVT
03-26-06, 10:12 PM
Hm only 18A? My Enermax 431W (over 4 years old) has 20A on the +12v.

It's possible that it has 18A on one of the +12v rails, and another 18a on another, but seeing as how another member has just stated he had problems with it with a 6800 Ultra, that's not good at all. :(

The Punisher
03-26-06, 10:18 PM
According to what I've heard, ur card should have come with a 6 pin to 2 separate 4 pin molex connectors rite? What u should do is connect the 2 molex connectors to 2 "separate" 12v rails & not plug both onto the same rail. Thats coz each rail has its own amp rating & so if u plug it separately then u'll get a total amp of more than 20A which is fine but if u plug it in the same rail then u'd be stressing ur PSU coz the card is drawing 20A from an 18A rail. Got it? Further more, 18A is the amp rating for a fully loaded rail meaning if the rail is just connected to ur card then the PSU doesn't give it the full 18A. U'll need to load the rail with ur hard drives, floppy, optical, etc in order to get the full 18A.

ReDxKiNG
03-26-06, 10:21 PM
Hm only 18A? My Enermax 431W (over 4 years old) has 20A on the +12v.

It's possible that it has 18A on one of the +12v rails, and another 18a on another, but seeing as how another member has just stated he had problems with it with a 6800 Ultra, that's not good at all. :(


To be honest with you,while im not a newb i dont know squat about power supplies, maybe you could take a look at this site for me http://www.thermaltake.com/purepower/W0026.htm and tell me if i have enough, i dont know crap about rails,voltage,amps etc etc as i never had to worry about that in my past experiences until now.

ReDxKiNG
03-26-06, 10:26 PM
According to what I've heard, ur card should have come with a 6 pin to 2 separate 4 pin molex connectors rite? What u should do is connect the 2 molex connectors to 2 "separate" 12v rails & not plug both onto the same rail. Thats coz each rail has its own amp rating & so if u plug it separately then u'll get a total amp of more than 20A which is fine but if u plug it in the same rail then u'd be stressing ur PSU coz the card is drawing 20A from an 18A rail. Got it? Further more, 18A is the amp rating for a fully loaded rail meaning if the rail is just connected to ur card then the PSU doesn't give it the full 18A. U'll need to load the rail with ur hard drives, floppy, optical, etc in order to get the full 18A.


thanks for the insight ,im starting to get a better understanding of how it works, I will try connecting them the way you stated and hopefully that will allow me to power my card properly.

ReDxKiNG
03-26-06, 11:05 PM
can someone check the graph on http://www.thermaltake.com/purepower/W0026.htm for my psu and tell me where I stand?

jcniest5
03-26-06, 11:20 PM
There are two things you can do now. 1) When the PSU arrives, test it out using everything you have and see how it performs. And depending on how well it holds up, you can then decide what to do next. Who knows, the PSU you ordered might work well despite its 18A. 2) Don't even open the PSU box, just RMA it at once and get a new one, knowing that the amp is a little too low to be on the safe side.

If you go with option 2 and have extra $$$ to spend, you can actually go ahead and order a better PSU now so you won't have to wait for your RMA to go through.

ReDxKiNG
03-27-06, 10:02 AM
There are two things you can do now. 1) When the PSU arrives, test it out using everything you have and see how it performs. And depending on how well it holds up, you can then decide what to do next. Who knows, the PSU you ordered might work well despite its 18A. 2) Don't even open the PSU box, just RMA it at once and get a new one, knowing that the amp is a little too low to be on the safe side.

If you go with option 2 and have extra $$$ to spend, you can actually go ahead and order a better PSU now so you won't have to wait for your RMA to go through.


Yea Im going to try option 1 along with what The Punisher said because from the way he described it I should be Fine if I do it according to the way he said it, I hope :(
Any more words of advice would be greatly appreciated seeing as you guys ARE prob bigger Enthusiast's than those at rage3d (which btw werent any help as they just suggested I scrap the 7800gs and go with an x850 >_< )

ReDxKiNG
03-27-06, 03:36 PM
anyone with a 7800gs or some experience in this matter care to comment?:hmmm:

betterdan
03-28-06, 08:08 PM
That power supply isn't listed as having 2 12v rails. It says it only has 1 and it is rated at 18A. I would send it back and get a better PSU for peace of mind.

The Punisher
03-29-06, 02:02 AM
That power supply isn't listed as having 2 12v rails. It says it only has 1 and it is rated at 18A. I would send it back and get a better PSU for peace of mind.

U r misinterpreting the information, it means only "one" rail out of the lot has an output of 18A & NOT as having just one 12V rail. The pic alone shows at least 4 rails on the unit. No PSU in the world has only a single 12V rail my friend.

betterdan
03-29-06, 06:30 AM
I don't know a whole lot about PSUs but I think you might be confused Punisher. Can you post what you are looking at in regards to it showing 4 12v rails? Lots of PSUs have 1 single 12v rail.
From my understanding PSUs that have more than 20A current capability on the 12V line are split into 2 or more rails to comply with the EN-60950 safety regulation which states that the maximum output power on user-accessible contacts must not exceed 240VA (that is, the current must not be higher than 20A at 12V voltage.

The Punisher
03-29-06, 11:46 PM
I don't know a whole lot about PSUs but I think you might be confused Punisher. Can you post what you are looking at in regards to it showing 4 12v rails? Lots of PSUs have 1 single 12v rail.
From my understanding PSUs that have more than 20A current capability on the 12V line are split into 2 or more rails to comply with the EN-60950 safety regulation which states that the maximum output power on user-accessible contacts must not exceed 240VA (that is, the current must not be higher than 20A at 12V voltage.

Ok i c where is the mistake, what i meant by "rail" is the number of power cables that the PSU has. So if according to the pic (http://www.thermaltake.com/purepower/W0026.htm), I count roughly 4 or 5 power rails divided into 2 large molex connectors each. Which is why I said 4 12V rails. Sorry for the miscommunication. My post is still correct though that the card's 6 pin connector needs to be plugged to 2 separate power rails to achieve the stated 20A that the card needs. Leadtek's 7900GTX cards even requires 350W PSUs capable of 22A & in SLI config requires a 500W PSU capable of a whooping 30A to run! (source (http://www.leadtek.com.tw/eng/3d_graphic/specification.asp?pronameid=256&lineid=1&act=2))

System 1:
AMD Athlon 64 3800+ (non o/c) / MSI K8N Neo2 Platinum /2 x 1024GB OCZ PC3200EL 2,3,2,6 1T dual channel / PNY 6800 Ultra 425/1100/ Seagate Barracuda 200GB SATA / Audigy 2 ZS / 16x dual layer cdr/dvdr burner / 48x cd/dvd / 470w Enermax / 19 inch NEC 97F
System 2:
P4 3.06 (non o/c) / Intel D845PEBT2 / 2 x 512GB OCZ PC3200EL 2,3,2,6 / EVGA 6800 GT 390/1100 / 2 x 120gb W.D. drives in raid 0 / Audigy 2 ZS / 4x cdrw/dvdrw / 48x cd/dvd / 430W Antec / FPD1750 17-inch LCD Monitor

Btw, u have some typos in ur sig. Its 2 x 512/1024"MB" & not GB ;)

betterdan
03-30-06, 07:23 AM
Btw, u have some typos in ur sig. Its 2 x 512/1024"MB" & not GB ;)
:rofl No really, I have 2x512 Gb in that rig.


Fixed. :D

ReDxKiNG
03-30-06, 06:44 PM
Ok i c where is the mistake, what i meant by "rail" is the number of power cables that the PSU has. So if according to the pic (http://www.thermaltake.com/purepower/W0026.htm), I count roughly 4 or 5 power rails divided into 2 large molex connectors each. Which is why I said 4 12V rails. Sorry for the miscommunication. My post is still correct though that the card's 6 pin connector needs to be plugged to 2 separate power rails to achieve the stated 20A that the card needs. Leadtek's 7900GTX cards even requires 350W PSUs capable of 22A & in SLI config requires a 500W PSU capable of a whooping 30A to run! (source (http://www.leadtek.com.tw/eng/3d_graphic/specification.asp?pronameid=256&lineid=1&act=2))



Btw, u have some typos in ur sig. Its 2 x 512/1024"MB" & not GB ;)


yes your absolutely correct, I did have to plug 2 separate power rails to achiece 20a, and sorry that i havent posted in a while..been too busy maxing out my settings in tons of games just to see the performance..it owns my 9700pro AND my psu works fine with it,thanks for all your help guys I REALLY appreciate it.IM never going back to ati again as far as agp goes anyway lol

ReDxKiNG
03-30-06, 06:53 PM
To tell you the truth This is my first nvidia card EVER and the first thing I did when i hooked it up yesterday was try out the "Digital Vibrance" thingie that all the nvidia heads have been yapping about for years and man let me tell you the difference in color is Amazing (of course you can always do the same effect manually on an ati card with the rgb sliders but this is much easier). I am officially in love with Nvidia. I FINALLY got to witness hdr in far cry(not to mention finally being able to play with all the settings on very high) and man let me tell you its beautiful, I can now run chaos theory on the 3.0 path and it looks nothing short of amazing as well with all settings maxed. Next game up to try is Oblivion and I cant wait. It turns out that my psu works fine with it even under heavy load on the card. This card IS cooler and quieter than my friends 6800 ultra. All in all i am VERY pleased with the performance this card has given me. I know my cpu is pretty much crappy(P4 2.4ghz 533fsb) and probably bottlenecks my card but i can still notice the HUGE speed increase at higher resolutions like 1280x1024 with hdr,4xaa,and 16x af.

The Punisher
03-30-06, 11:15 PM
Glad to hav been help to ya. Rock on dude.

betterdan
03-30-06, 11:59 PM
I learned something also from Punisher.
One question though, I have a 7800GTX and it is using one of the PCIE power cables from the power supply. My Antec TP II 550w PSU has 2 12v rails with 19A on each. Since I am only using 1 cable for the card does that mean the max it can get is 19A?

The Punisher
04-02-06, 01:30 PM
If the 6 pin PCIE power cable is direct from the PSU without needing the connector that came with ur card then the PSU "should" be giving the card all the juice it needs. I can't confirm that little bit of info but from what I've read nVidia in-house testers use Antec PSUs in thier test PCs to check for compatibility issues.