Another, can my power supply handle this system thread:

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known12345

Limp Gawd
Joined
Nov 17, 2007
Messages
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My power supply: Corsair HX520w (great performance and aesthetics)

System:

Maximus II Formula
Q6600
G.SKILL 4GB (2 x 2GB) DDR2 1000
8800gt
2 hd (1 80 GB VR, 1 300 GB Maxtor)
1 cd burner

Currently, the my psu is more than enough for my current system but I was thinking of upgrading into a crossfire system as the 4800 series drops in price. Now I was wondering, is my psu, including my system compatible with:

1. 4850
2. 4870
3. 4850, 4850
4. 4870, 4870
5. 4870x2
6. 4870x2, 4870x2

I've looked at various sites to try to answer my question, but none of them have given concrete direct answers:

ATI Radeon™ HD 4800 Series – System Requirements

Power Supplies Certified for Single Card Operation

AMD Radeon HD 4800 Series [H] review, Power Draw Total System Wattage at Wall

The last link seems to provide the most useful info. In the "Full Load Power" column it shows the various cards and a wattage number. Now is that number including their system as well, or is it just the video cards?

I am pretty sure numbers (1) and (2) are for sure and number (6) is completely false however the rest I am unsure. Also, please assume I will overclock my cpu from 2.4 to 3.6 (if I am running a crossfire system, which I hope to do eventually, I don't want my cpu to be the bottleneck).

Edit 1: I guess I should mention that I am very confused because every time I see an SLI or crossfire system in a sig, it seems that the person generally has ATLEAST an 800 watt psu, usually a 1000 watt and i really dont wana have to buy a new psu.
 
known12345 said:
My power supply: Corsair HX520w (great performance and aesthetics)

<snip>

I am pretty sure numbers (1) and (2) are for sure and number (6) is completely false however the rest I am unsure. Also, please assume I will overclock my cpu from 2.4 to 3.6 (if I am running a crossfire system, which I hope to do eventually, I don't want my cpu to be the bottleneck).

Edit 1: I guess I should mention that I am very confused because every time I see an SLI or crossfire system in a sig, it seems that the person generally has ATLEAST an 800 watt psu, usually a 1000 watt and i really dont wana have to buy a new psu.
Click to expand...

If you factor in a conservative effeciency for the PSU at 80% in the [H] review the the crossfired 4870 system only taxes the PSU with a little under 370W which your current PSU should have NO trouble handeling. As for crossfiring X2 cards with your current system Crossfiring two 4870X2 would need a PSU that could sustain 650W under load going by the [H] reviews numbers.

The reason for going overboard (as 800W PSU for a 400W effective draw) with the PSU even then is that if you aim to only tax your PSU 50-60% you'll generally max out the efficiency of the unit resulting in less energy waisted as heat (result is a cooler running system) and improve the longvity of your PSU...
 
Darth Bobo said:
If you factor in a conservative effeciency for the PSU at 80% in the [H] review the the crossfired 4870 system only taxes the PSU with a little under 370W which your current PSU should have NO trouble handeling. As for crossfiring X2 cards with your current system Crossfiring two 4870X2 would need a PSU that could sustain 650W under load going by the [H] reviews numbers.

The reason for going overboard (as 800W PSU for a 400W effective draw) with the PSU even then is that if you aim to only tax your PSU 50-60% you'll generally max out the efficiency of the unit resulting in less energy waisted as heat (result is a cooler running system) and improve the longvity of your PSU...
Click to expand...

WOW thank you so much for all the info, was very helpful. Honesty, didn't know a thing about PSU till after reading our post, especially about the "going overboard" part. Still a little cloudy on the whole "generally max out the efficiency of the unit resulting in less energy waisted as heat" due to having a higher rated PSU (not exactly where the wasted heat could come from if your system was running at a rated wattage almost equal to your rated PSU). Though I have no doubt my lack of understanding is due to my little knowledge of PSUs. In any case, thanks for the help. To compensate for the increase heat, should I direct a fan to my psu?
 
Its the theory that if your system draws 450 watts, a 500 watt PSU will be at 90% load, which means that it will produce more heat than a 1000 watt system running at 45% load.
 
twoeyes said:
Its the theory that if your system draws 450 watts, a 500 watt PSU will be at 90% load, which means that it will produce more heat than a 1000 watt system running at 45% load.
Click to expand...

No. That's not true.
Generally the AC power draw and heat generated will be insignificantly different between the two power supplies assuming they are of the same quality and construction.

Of course if you find the most inefficient 500W power supply in the world and compare it to the most efficient 1000W power supply, you will see a significant difference.

Let's work this out:
Heat == Energy
Energy = Power*Time

Load doesn't make a difference in calculating heat. (Load may make a difference in how stable the power supply is since pushing components close to their designed limits will generally wear them out a bit faster and/or increase the chance that one components will be out of spec and may fail.)
 
The HX520 can run any single card on the market right now fairly easily. If you're going high-end SLI/Crossfire, an HX620 or TX750 would work better.

If you're going 3-way SLI or Quad Crossfire, I recommend the HX1000.

Another benefit of overkill is that the fan in the PSU won't spin up too loud when the PSU is only loaded 50-60%. That may not matter, though, because if you're loading up the PSU, you've probably got a game running, and the GPU fans are going to be way louder than the PSU fan anyway.
 
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