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Power Supplie worries with Graphics Cards

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December 5, 2009 6:14:18 PM

I currently own a CiT 750W PSU dual 12v rails, with these specs - 3.3V 28A 5V 30A 12V(1) 20A 12V(2)20A -12V 0.3A 5Vsb 2.5A
Either this - http://www.play.com/PC/PCs/4-/8284366/CiT-Silent-Techno...
or this - http://www.play.com/PC/PCs/4-/8903144/CiT-750U-750W-PSU...

I don't know much about PSU's, but I currently run a HD 2600XT 512 GDDR3, runs fine, no problems.
I'm either going to be (most likely) buying a GTX 260 216 or a HD 4890.
The PSU is SLI capable (just saying).
But will the 20Amps on each rail be fine?
and it only has 1 6Pin PCI-e connector, I would use a 4pin(s) molex to 6Pin PCI-e adapter connection for the other power connection on the GPU, but even if the amperage counts as 40Amps (both added together) for the 12V rails,
WILL IT WORK?!!!???!!!??!!!!
I don't want any of my new parts ruined of my gaming rig.
Asus P5Q Premium
2X2GB Crucial Ballistix Tracer RAM DDR2-800
Core 2 Quad Q6700 (probably upgrade later on)
and of course the GPU and PSU.
I hope it is capable of working.
Just thought since it was SLI capable and is 750W, they wouldn't expect you to use 2 low end NVidia GPU's (motherboard is CrossFire only, won't be using CF, unless I go ATi, in which case, I'll have to change PSU later on).
a c 248 ) Power supply
a b U Graphics card
December 5, 2009 6:33:59 PM

For a 750 watt power supply the current (amps) on the +12 volt rails appears to be low.

The general rule of thumb is a high quality 500 to 550 watt power supply with sufficient current (amps) on the 12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the 12 volt rail(s) can power a system with two video cards operating in dual mode. There are a few exceptions like the new ATI Radeon HD 5XXX series cards which use less power due to their energy efficiency.

A high quality 500 to 550 watt psu will have a +12 volt rail rated at 40 amps. A high quality 700 to 750 watt psu will have a +12 volt rail rated at 60 amps.

In addition the power supply should be at least 80+ Bronze certified for energy efficiency.

Corsair, PC Power & Cooling, and Seasonic are some of the brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty. Lately we've been seeing a few other brands offering some high quality units. An example would be the Antec Earthwatts series which is an improvement over Antec’s older psu's like the low budget Basiq models.

December 5, 2009 11:26:51 PM

(I am new to Tom's Hardware, just letting you know).
Yeh, But I don't want to be going out buying PSU's constantly. and I don't have the money right now.

Though would you say I could run a 4870, 4890, GTX 260, or a 5770 on this PSU, with no problems?

And if you're not sure if it will work, can anything go wrong (with parts), like things break. I don't want a PSU, GPU, Motherboard, or CPU etc, or anything to break, only a teen, and don't have money to re-invest in parts).
Thanks for replying! :) 
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a b U Graphics card
December 5, 2009 11:43:29 PM

a 5770 should be fine. the others may be alright, but the low power PSU may have issues.

right now though, i wouldnt recomend anything other than a 5xxx series GPU to anyone buying a new card. so id say go for a 5770 anyway. it only drawes a small ammount of power so should be fine under that psu.
a c 248 ) Power supply
a b U Graphics card
December 6, 2009 12:20:45 AM

It should be able to power a system with a single video card. I don't see a problem there. However, I think it might have a problem powering an overclocked system with two video cards operating in dual mode during a hardcore gaming session. It's difficult to say because I am in the USA and I don't know anything about CIT power supplies which are sold in the UK. As previously mentioned I simply noticed the current (amps) on the 12 volt rails is low. The 40 amp rating is what I would expect to see in a high quality 500 to 550 watt power supply. Between the low current and what I assume to be a bargain price in the UK it appears the psu is a low budget model. At least I assume it is a bargain price because I looked at the vendor's web site and saw the prices for high quality Corsair power supplies.
a c 139 ) Power supply
a c 230 U Graphics card
December 6, 2009 12:29:21 AM

If you are operating the machine at stock w/ no overclocking, i wouldn't worry about it. I would not add a 2nd GFX card nor invest in any serious overclocking hardware with that PSU however.

If you are going in that direction....I'd suggest visiting the link below and seeing if you can fit one of the Editor's Choice models into your budget. If not, the "recommended" category will adequately serve all but the most demanding enthusiast.
December 6, 2009 12:56:21 AM

JackNaylorPE said:
If you are operating the machine at stock w/ no overclocking, i wouldn't worry about it. I would not add a 2nd GFX card nor invest in any serious overclocking hardware with that PSU however.

If you are going in that direction....I'd suggest visiting the link below and seeing if you can fit one of the Editor's Choice models into your budget. If not, the "recommended" category will adequately serve all but the most demanding enthusiast.


Well I will only be having a Single GPU configuration with this PSU, my motherboard is CrossFire only, and this PSU is SLI only so only a Single GPU can run.
But I would rather go NVidia just for PhysX, CUDA, and almost all my games need that extra NVidia architecture boost.

So do you reckon it could still run a GTX 260 or a 4890? Non OC'd, and my RAM and my CPU aren't OC'd, I won't be OC'ing don't worry.

Though will it be fine with a 92 (think so) MM fan, 2x 120MM fans (in case) a Q6700 (Is it power hungry?) P5Q Premium (when I get it for X-mas, currently have a Foxconn P4M9007MB-8RS2H) etc.
Just don't want anything going wrong. :) 
So, even if I have no OC's, nothing can go wrong right?
I still don't want a PSU failure, even if a PSU dies, and nothing else does, I don't want to re-invest.

What temps would you say 4870's, 4890's and GTX 260's get at?

Thanks though dude, hope you can help me out just finalizing that my PSU is okay :) 
December 6, 2009 12:57:47 AM

JohnnyLucky said:
It should be able to power a system with a single video card. I don't see a problem there. However, I think it might have a problem powering an overclocked system with two video cards operating in dual mode during a hardcore gaming session. It's difficult to say because I am in the USA and I don't know anything about CIT power supplies which are sold in the UK. As previously mentioned I simply noticed the current (amps) on the 12 volt rails is low. The 40 amp rating is what I would expect to see in a high quality 500 to 550 watt power supply. Between the low current and what I assume to be a bargain price in the UK it appears the psu is a low budget model. At least I assume it is a bargain price because I looked at the vendor's web site and saw the prices for high quality Corsair power supplies.


Not having a go, but just hoping you did notice it's 20A per +12V rail.
How does the GPU work, does it need to draw the Amps from one rail?
December 6, 2009 1:40:55 PM

JackNaylorPE said:
If you are operating the machine at stock w/ no overclocking, i wouldn't worry about it. I would not add a 2nd GFX card nor invest in any serious overclocking hardware with that PSU however.

If you are going in that direction....I'd suggest visiting the link below and seeing if you can fit one of the Editor's Choice models into your budget. If not, the "recommended" category will adequately serve all but the most demanding enthusiast.


Right, I need to go NVidia really, just got Mirror's edge, and taking into account almost all my games are 'NVidia, The way it's Meant to be Played!'.
So with no CPU, RAM, FSB, or GPU overclocking, basically no overclocking at all, would a GTX 260 (216 cores) be fine!?

If it will, then I will order "A" GTX 260 216 soon.
a c 248 ) Power supply
a b U Graphics card
December 6, 2009 2:10:07 PM

Yes, I did notice that the psu claims to have two +12 volt rails rated at 20 amps each. Again, that is low for a 700 watt power supply.

Adding the current (amps) usually does not provide the actual combined total. The actual total for high quality psu's will be somewhere close but the low budget psu's will have an actual total that is lower. Sometimes the actual total of the low budget models can be significantly lower.

The +12 volt rail powers the video card, cpu, and several other components. The rail supplies about 70% of the power to a pc system.

We have a problem with multiple +12 volt rails. The vast majority of power supplies which are advertised as having multiple rails do not have true separate rails. They typically have one large rail. Instead think of them as "virtual rails". It was advertising gimmick. A few years ago there was a big stink about it. There are a very small handful of power supplies that have actual separate rails. There aren't very many of them. Most of them are very high end, high wattage models. There's an even smaller number in the mid-range. For the typical user or typical gamer it doesn't make much of a difference.

Power supplies come with 75 watt, 6 pin, PCI-Express power cables and/or 150 watt, 8 pin, PCI-Express power cables that match the power connections on video cards so it is just about impossible to screw things up. Nothing to worry about.
December 7, 2009 11:33:50 AM

JohnnyLucky said:
Yes, I did notice that the psu claims to have two +12 volt rails rated at 20 amps each. Again, that is low for a 700 watt power supply.

Adding the current (amps) usually does not provide the actual combined total. The actual total for high quality psu's will be somewhere close but the low budget psu's will have an actual total that is lower. Sometimes the actual total of the low budget models can be significantly lower.

The +12 volt rail powers the video card, cpu, and several other components. The rail supplies about 70% of the power to a pc system.

We have a problem with multiple +12 volt rails. The vast majority of power supplies which are advertised as having multiple rails do not have true separate rails. They typically have one large rail. Instead think of them as "virtual rails". It was advertising gimmick. A few years ago there was a big stink about it. There are a very small handful of power supplies that have actual separate rails. There aren't very many of them. Most of them are very high end, high wattage models. There's an even smaller number in the mid-range. For the typical user or typical gamer it doesn't make much of a difference.

Power supplies come with 75 watt, 6 pin, PCI-Express power cables and/or 150 watt, 8 pin, PCI-Express power cables that match the power connections on video cards so it is just about impossible to screw things up. Nothing to worry about.


Wow, thanks for letting me know it won't screw things up.
So do you reckon it can run a GTX260? (non-oc Core 216)
a c 248 ) Power supply
a b U Graphics card
December 7, 2009 12:50:26 PM

yes.
December 8, 2009 12:04:56 PM

JohnnyLucky said:
yes.


Well, I guess thanks (and for your time replying) :D 

So, I'll let you know when my rig's running. :) 

Right now on ebuyer, the GTX 260 216 Point Of View seems to be the best (for the money).
Quick find code is - 179590
Can you make sure it's not Factory OC'd...
Thanks :) 
a b ) Power supply
a b U Graphics card
December 8, 2009 10:42:37 PM

JohnnyLucky said:
We have a problem with multiple +12 volt rails. The vast majority of power supplies which are advertised as having multiple rails do not have true separate rails. They typically have one large rail. Instead think of them as "virtual rails". It was advertising gimmick. A few years ago there was a big stink about it. There are a very small handful of power supplies that have actual separate rails.

And ironically the big thing now is going back to the single 12v rail set up.
a c 248 ) Power supply
a b U Graphics card
December 9, 2009 1:41:11 AM

Alistair - That video card is not overclocked. I checked a several references. You'll be okay.
!