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GPU connector advice (and power question)

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  • PCI Express
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Last response: in Graphics Cards
February 5, 2013 10:42:44 AM

Bought a basic Zoostorm computer for my son.

Trying to fit a graphics card to it (nothing too high powered, just an improvement on the integrated graphics)

The PC's PSU is a LPA-300C, 300W total output. The CPU is only an Intel G840, I'm trying to put a Radeon HD 3850 into it.

So, two questions:
1. Will the GPU overload the PSU and kill the machine?
2. The PSU has lots of 4-pin MOLEX connectors coming out of it, but no 6-pin PCI-E connector (despite the motherboard having a PCI-E slot). Can I just get a convertor from Molex ->PCI-E or does this need a whole new PSU?

More about : gpu connector advice power question

February 5, 2013 10:54:13 AM

Seem to have answered my own question 2 - £3 gets me a 2xMOLEX -> PCI-E connector. Just the first question to worry about now!

(Sorry, system won't let me edit the OP)

The full PSU rating is:
+5V: 18A
+12V: 12A
-12V: 0.5A
+3.3V: 16A
+5VSB: 2A
Total 300W
a c 104 U Graphics card
February 5, 2013 11:37:31 AM

it'll likely fry the psu... 12amps on the 12 volt rail means 144 watts for all the power hungry parts combined and that is not much. And if the card has pcie power connector it means the card is rated between 75-150 watts... Wont leave much left for the rest of the system. Better to upgrade the psu as well, some good quality brand with 400-500W should be quite enough. (corsair, antec, silverstone etc..)
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February 5, 2013 12:01:55 PM

Hmm, now I have the question of whether to return the PC (only cost me £175) and get one with a better PSU - and maybe slightly higher spec (G840, 6Gb RAM, 250Gb HDD, no OS.

Or do I stick with what I've got (which is probably a good enough spec, GPU and PSU aside) and spend a few quid upgrading the PSU.

PSU upgrade feels the cheapest option. Especially if this is likely to be sufficient:
CIT 450w Gold 12CM Silent Atx Power Supply
February 5, 2013 12:51:46 PM

Ha! OK, fair comment. Are Coolermaster any good?

(Sorry to pester, but every penny is vital on this build!)

a b U Graphics card
February 5, 2013 1:42:45 PM

First, the PSU you have is what most would consider that is is best used as as door stop and never to grace in inside of a computer.
Unforunatley that is the case for just about all store bought budge systems.

With a 3850 A 300 Watt PSU will handle it. The GPU only draws about 60Watts loaded (less than 15 watts @ idle). CPU about 75 Watts 100% load (Idle = <40 Watt) My est is your system w/3850 would be under 150 Watts loaded
In your case, your +12 V is limited to 144 Watts (GPU + CPU loaded = 135 Watts Factor in a DVD drive and a HDD Plus other circuitry that draws power from the +12V rail - NOT A GOOD idea.

Recommend PSU 400->450 Watt, Brands Corsair, Seasonic, Antex (not all)
Look for Bronze ie
I know you are in England so prices are different. - NOTE England or USA you get what you pay for

CM does offer some good PSU's just not in the lower cost models.
Rosewell even ofers some good PSU - Most of them stink.

PS while a 300->350 watt PSU would be fine, not really any cheaper than a good 400->450Watt.
Plus with a 430 Watt you could move up to a much better GPU say a 6750
a c 104 U Graphics card
February 5, 2013 2:15:44 PM

btw jonnyguru has some good psu reviews (the language is a bit colorfull but there is plenty of know-how underneath).
Here is the review on the corsair cx430 v2 I linked before:
and here is a cheap unit off ebay:

quite different results.

It's quite surprising that the 3850 maxes out at 60W, they could have powered it via the pcie slot alone, maybe they went for the safer option with the 6pin pcie power...
February 5, 2013 2:32:47 PM

Went for that Corsair cx430. Thanks for the help everyone.