• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

Good deal for a 750W PSU?

It's a good powersupply, but your current PSU might be able to handle your rig just fine. Not long ago you could actually get that 850w version for 80$ !!! But for 120$, hmz, you might want to consider a 520/620hx instead, because it's modular, which is really a plus if you ask me. 520hx should in fact, for 90$ or so, be able to handle anything you buy just fine.
 
For the love of god you don't need a 750W PSU for that, are you serious? The only thing it's good for is giving a bigger number on your electricity bill. You're fine with your current PSU.
 
Originally posted by: Scoop
For the love of god you don't need a 750W PSU for that, are you serious? The only thing it's good for is giving a bigger number on your electricity bill. You're fine with your current PSU.
Click to expand...
Actually that is a misconception. A 300W load on a psu is the same no matter what the wattage rating of the psu listed as. It's the efficiency of the psu that plays a vital role on the amount power that is required from the wall socket. That 200W load on a 300W psu that is only 70% efficient will require 429W from the wall, and if the 750W is 80% efficient it will only require 375W. Therefore in this case the higher wattage psu saves you money on your electric bill.

1000(kWhr)/54(wattage difference)*.15(cents per kWhr)*24(hours)*365(year)=$70.96 (yearly savings)
 
Originally posted by: John
Originally posted by: Scoop
For the love of god you don't need a 750W PSU for that, are you serious? The only thing it's good for is giving a bigger number on your electricity bill. You're fine with your current PSU.
Click to expand...
Actually that is a misconception. A 300W load on a psu is the same no matter what the wattage rating of the psu listed as. It's the efficiency of the psu that plays a vital role on the amount power that is required from the wall socket. That 200W load on a 300W psu that is only 70% efficient will require 429W from the wall, and if the 750W is 80% efficient it will only require 375W. Therefore in this case the higher wattage psu saves you money on your electric bill.

1000(kWhr)/54(wattage difference)*.15(cents per kWhr)*24(hours)*365(year)=$70.96 (yearly savings)
Click to expand...

What math are you doing to calculate the wattage pulled from the wall?

By my understanding, a 70% efficient PSU transfers 70% of the power from the wall into usable juice for the PC. So to figure out how much wattage a 70% efficient PSU needs from the wall to supply 200W to the PC, we use this equation:

.7(x) = 200W

Dividing both sides by .7, we get that x, the power from the wall, equals ~285W.

For the PSU that's 80% efficient, we start with this:

.8(x) = 200W

and find x to be 250W.

There's still a difference, but it's smaller than you made it out to be. I'm wondering where you came up with 429 and 375.

Regardless, this has nothing to do with the size of the power supply, only its efficiency. Also, my understanding is that some PSUs are less efficient if they're running below half of their maximum load, which may make it less cost-effective to run a larger PSU. (This depends, however, on the particular unit's efficiency curve.)

As far as the original post, a modern computer with a dual-core processor and an 8800GT draws at most something in the neighborhood of 200-250W from the wall at full load. A quality 400W PSU is plenty to power your upgrades. Your old PSU is probably sufficient, assuming it can supply the necessary amperage on its 12V rail(s). If it can supply more than 25A using some combination of the +12V rails, you should be fine.
 
Originally posted by: DSF
Originally posted by: John
Originally posted by: Scoop
For the love of god you don't need a 750W PSU for that, are you serious? The only thing it's good for is giving a bigger number on your electricity bill. You're fine with your current PSU.
Click to expand...
Actually that is a misconception. A 300W load on a psu is the same no matter what the wattage rating of the psu listed as. It's the efficiency of the psu that plays a vital role on the amount power that is required from the wall socket. That 200W load on a 300W psu that is only 70% efficient will require 429W from the wall, and if the 750W is 80% efficient it will only require 375W. Therefore in this case the higher wattage psu saves you money on your electric bill.

1000(kWhr)/54(wattage difference)*.15(cents per kWhr)*24(hours)*365(year)=$70.96 (yearly savings)
Click to expand...

What math are you doing to calculate the wattage pulled from the wall?

By my understanding, a 70% efficient PSU transfers 70% of the power from the wall into usable juice for the PC. So to figure out how much wattage a 70% efficient PSU needs from the wall to supply 200W to the PC, we use this equation:

.7(x) = 200W

Dividing both sides by .7, we get that x, the power from the wall, equals ~285W.

For the PSU that's 80% efficient, we start with this:

.8(x) = 200W

and find x to be 250W.

There's still a difference, but it's smaller than you made it out to be. I'm wondering where you came up with 429 and 375.
Click to expand...

Your math is correct. John might be a bit tired tonight. 😉

But the point that John makes does remain, and since the older Powerstream 520W is less efficient than the more current Cooler Master 750W, it would actually be cheaper to run the Cooler Master than the Powerstream.

Unfortunately, it'll take about 10 years of 24/7 use for you to save enough to pay for the PSU. 🙂

So keep the existing PSU, and if problems crop up because of not enough power on the +12V or the age of the unit, etc. THEN replace it. Don't replace it simply because you THINK you need a bigger PSU. An 8800GT can run on a good 500W. SLI on a good 550W.
 
Originally posted by: DSF
There's still a difference, but it's smaller than you made it out to be. I'm wondering where you came up with 429 and 375.
Click to expand...
I failed to proof my reply, and the 200W should read 300W. 😱

300/.7=429
300/.8=375

Regardless, this has nothing to do with the size of the power supply, only its efficiency.
Click to expand...
I stated that as well. 🙂

 
Actually the point I was trying to make was that with a 750W PSU that system runs at around 170W idle resulting in a ~23% load for the most time. Can you actually seriously in all honesty say that a PSU is at it's most efficient at 23% load? Where as the 520W PSU would be running mostly at ~33% load which is a whole lot better. Of course I don't know excatly what kind of efficiencies these two units have at that level, so if the OCZ PSU is a total POS then my bad.
 
Originally posted by: John
Originally posted by: DSF
There's still a difference, but it's smaller than you made it out to be. I'm wondering where you came up with 429 and 375.
Click to expand...
I failed to proof my reply, and the 200W should read 300W. 😱

300/.7=429
300/.8=375

Regardless, this has nothing to do with the size of the power supply, only its efficiency.
Click to expand...
I stated that as well. 🙂
Click to expand...

Must have missed it. Cheers. 🙂
 
Originally posted by: Scoop
Actually the point I was trying to make was that with a 750W PSU that system runs at around 170W idle resulting in a ~23% load for the most time. Can you actually seriously in all honesty say that a PSU is at it's most efficient at 23% load? Where as the 520W PSU would be running mostly at ~33% load which is a whole lot better. Of course I don't know excatly what kind of efficiencies these two units have at that level, so if the OCZ PSU is a total POS then my bad.
Click to expand...


I wouldn't say that the OCZ is a total POS. It's just "old school" by today's standards where 80%+ efficiency wasn't such a concern.

The OCZ never gets to 80% efficiency, so I don't care what the OP's load actually is. 😛 The Cooler Master IS 80% efficient, even at only 20% load.


 
Don't know if you've bought a PSU yet or not, but, Buy.com has the Corsair TX750W for $100 after $45 rebate. Seems like the general consensus is that you don't need a PSU this powerful, but, if you're going to spend that amount of money, might as well get one with some headroom.
 
Check the Hot Deals forum... I think the Cooler Master 750W PSU is available for around $50 after a $50 rebate.
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top