Power supply advice

[film2240]

Hi guys,
I was looking at power supplies as I may need something more efficient as the electric bills have gone up considerably.

Every since I got my Radeon HD 6950,overclocked it (895MHZ core clock and 949 MHZ mem clock) and unlocked its shaders as well,I notice that the power draw from the wall rises to over 310W for no clear reason even though it used to use under 300 Watts from the wall.

My PSU is:
An Enermax liberty 620W
I got this in summer 2007
The efficiency is only 80% though

If I was to upgrade to a more efficient power supply (like 90% or more) how much would my power use drop?
Is this even a worthwhile upgrade?
I only have 2 HDDs (Boot volume will be replaced by SSD but most SSDs I saw from the reviews have reliability problems)

Can someone who can recommend me an SSD thats:
1.Uses little energy
2.High performing
3.Has no history of failing
4.No more than 120GB in capacity due to budget (however the bugdet does allow for an SLC based drive in certain circumstances)

Thank you

[1713994388]

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[mikeo]

Efficient PSus are really nice, but I question the economic validity of your possible upgrade. PSUs in the 90% efficiency range are not cheap and it seems to me that the payback would take a very long time. If you just want to be green, that's another matter.

SSDs are truly the best advance in computer hardware performance in the last 5 years IMHO. They all are very low power compared to spinning disks and if it were me, I'd be looking for a second generation used SSD like a OCZ Vertex/Agility or even an Intel to keep the cost down.

[deslok]

to answer your PSU question
the increase in power consumption at the wall is because you have overclocked your card. at 310w you could save some buy getting a PSU that's 80 plus gold or platnimum but it would take months to repay the cost of the new psu.
As far as SSD's are concerned i'm going to point you to this article
http://www.tomshardware.com/reviews/best-ssd-caching,2966.html

[Oldminer]

I have 2 x A-Data ssd's running in Raid0 and am very happy with them.

A-Data support is also second to none.

[film2240]

Efficient PSus are really nice, but I question the economic validity of your possible upgrade. PSUs in the 90% efficiency range are not cheap and it seems to me that the payback would take a very long time. If you just want to be green, that's another matter.

SSDs are truly the best advance in computer hardware performance in the last 5 years IMHO. They all are very low power compared to spinning disks and if it were me, I'd be looking for a second generation used SSD like a OCZ Vertex/Agility or even an Intel to keep the cost down.

I think that just focusing on the PSU is stupid unless the whole system is changed to be more energy efficient.

SSDs are what I planned to use anyway as my boot drive.I did see that Intel and Plextor (yes they make SSDs,but they're based on intel designs from what I can see anyway) have the fewest problems in terms of reliability if I buy now,If I hold off by even 2 weeks,I can get an SLC based SSD instead of the common MLC type (due to limited lifetime especially when used,so not worth the trouble for me.I don't wish to play russian roulette with my valuable data just because I decided to get an SSD instead of a Velociraptor.)

My 750GB Storage HDD will be replaced with a 'green' 2TB HDD (as I really need the space at the same time as shaving a few watts off,plus keeping the heat/noise down)

My PC lets me switch off all case fans at will for silent mode (with max power savings of course).I save 25Watts when in silent as the fans aren't spinning,plus 20 Watts more by switching my drives (SSD boot+2TB green hdd as all older drives will be off and removed)

Anyways,thanks for hte suggestion mikeo,however if you upgrade a PSU you should buy one with extra watts and much higher efficiency as buying an average PSU with low efficiency is a waste of time and money.

[teukon]

I honestly think that there is a big difference between 80% and 90% efficiency, enough to dwarf all other considerations apart from the voltages of the cards.  Ideas such as:
- Using 1 stick of RAM rather than 2;
- Underclocking the CPU;
- Booting from a USB drive or over ethernet to save on a HDD;
- Switching off USB/SATA/Firewire/Sound in the BIOS if you are not using them,
are all near-enough trivial compared to getting the voltages of the cards right and a high efficiency PSU, particularly if your system uses more than 1 card.

I think that just focusing on the PSU is stupid unless the whole system is changed to be more energy efficient.

This is just wrong.  An efficient PSU is more important if the rest of your system is inefficient.  You will be saving more watts with the upgrade.

Beware: I'm about to start doing calculations and I have a reputation for making bad assumptions.  Take this with a pinch of salt.

Suppose you have a system consuming 400W with a PSU which is 80% efficient at that power draw (so it's pulling 500W from the wall and is only able to provide 80% of that to the system).  If you swap the PSU out for one that can provide 400W at 90% efficiency then you power draw at the wall will fall to 444W, saving 56W.

Of course, depending how much power costs you and how long you expect to be running the miner for it may not be cost effective to go with a more efficient PSU.

[film2240]

Thanx for that teukon.

The rest of my system parts are in power savings mode except the GPU.
My system runs with the following settings:
Core i7 920 underclocked to 1.35GHz
RAM is underclocked (as this is automatic when the CPU is underclocked) (Saved me 30W combined with RAM and CPU underclocking/undervolting)
Only 2 HDDs run at the moment (3rd HDD was unplugged saving me 8W)
Green ethernet is enabled (this saves energy when using the ethernet port.Saved me about 10watts as cable is 20M long)
Firewire is already disabled (Saved me 5-10Watts)
Mobo chipset is undervolted and heavily underclocked,voltage drop is deep (As EPU-6 S/w auto does this for me without destabilising my system,soft mode in this doesn't make much of a difference.deep means max power savings on chipset) Intel X58 is my chipset
USB is active as my KB+Mouse need to run
SATA is active as my HDDs need to run
Once SSD is added,the IDE boot drive (yes I know it's super old,but that was only for testing purposes for when I first installed win 7 x64 2 yrs ago when I moved away from XP x64 for good.) will be gotten rid of meaning I can finally disable IDE/e-SATA chipset on my mobo as well).
Case fans are on slow (as they have good airflow without noise and high power use.saved me 15w from full speed to slow)

Since there isn't much more I can do with my mobo power savings,A more efficient PSU is worth considering.

The only card I have is my GPU.is it possible to undervolt a GPU and still get more performance than you would at stock?and how much energy can you get by undervolting a GPU while getting pretty good performance?

If you know of any PSus that are particulary efficient at the load of my machine (just teh GPU makes it jump from 105Ws idle to 310W,without anything else being active),please link to them,thank you :-)

[deslok]

Yes it is possible to increase the clock while undervolting the graphics card however your results will vary.
as far as a more efficent psu  you want one that is rated at 80 plus platnium those must reach 90% efficency at 20% load and 92 at 50% load (about where yours is running now.) and is in the 550-700w range.
however those could be very expensive it's 150 dollars for the only one newegg carries(550w)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817121080
without knowing your cost of electricity i can only make an assumption as to it's payback period if you were to mine 24/7.
the 12% increase in efficency would save you 37w at .15 per kwh you'll save ~93cents per week. a payback of over 3 years(which will decrease if you pay more than 15 cents per kwh.)
you could save yourself 40 dollars and go with a 80 plus gold instead
http://www.newegg.com/Product/Product.aspx?Item=N82E16817121078
this would run around 90% efficent at your normal load which would change your savings to
31w at .15 per kwh is ~ 78 cents per week which will be a payback period of 2 3/4 years(which will decrease if you pay more than 15 cents per kwh.)

[film2240]

my current elec costs are £0.23 per Kwh rising to £0.25 per Kwh from aug this year.I'm based in UK so will need UK sites and pricing.

Which is the best manufacturer for PSUs (is it still Enermax?) that can also be highly efficient?

I think of upgrading my PSu for 2 reasons:
1.To support future builds with more GPUs
2.To boost my effiency with current and future builds

Which can support tri-cross fire,as my mobo only has 3x PCI-E x16 (V2) slots?

I know that the most efficient and high power PSUS are not the cheapest but I see this as a thing that needs to last several computer builds in the future as well.(My current PSU has lasted for 2.5 builds.It's only 2.5 because my current build has had a GPU upgrade quite recently and not a full system overhaul as that would cost me too much)

[deslok]

you won't want to use tri crossfire for mining it's bad for performance but you'll want a 1kw psu for that normally.
one like this would do well
http://www.newegg.com/Product/Product.aspx?Item=N82E16817256068
be warned though that running a high wattage psu at a low load rating can have a negative impact on efficency so it may not reach optimal efficency until you add at least one more video card.

[teukon]

Wow!  I'm impressed with the large savings you are making by tweaking your BIOS.  switching off firewire for 5W, man!  When I switched off firewire the only detectable difference was that the firewire port wasn't lit up, the power drain didn't change at all for me.

In this case I stand corrected and do absolutely set about tweaking your BIOS as much as you can.  But even so, the efficiency of the PSU could save/cost you 50W so is worth considering at least.

I'm afraid I can't advise on PSUs.  I only have one miner and I bought my PSU with noise as the primary consideration.  For me the PSU is critical in building a mining rig (along with the cards and motherboard).  The chip, drives, RAM, OS, et cetera are good to get right but of secondary importance.  I personally never skimp on the power supply but for maximum profit you may want to go with something cheapish which can manage 86%+ at your mining load.  A typical positive attribute and one many people pay a lot for is for the PSU to be at least x% efficient at any load - give that you really don't need this shop around and look at the efficiency vs. load graphs for cheap PSUs.

As for voltages on the cards it really depends what you want out of your system.

• To maximise MH/J you will probably want to drop the voltage quite a bit (0.1V or more) and a little more still if you have many cards in one rig.
• To maximise profit then you may want to overvolt your cards by a small amount (0.05V is my guess) but this is assuming you have cooling sorted.
• To maximise MH/s then I find 1.25V is best (higher voltages hurt my stability due to the increased heat).

Of course, there are many factors: The cost of power; The market value of bitcoins; Your cooling; Your noise tolerance; How good at overclocking your particular cards are; even the OS!  I would get a PSU which is efficient at the power you expect to draw and for +/- 30%, use a power meter to measure power consumption at the wall, find your maximum stable clocks for a range of different card voltages and note power consumption/temperature/noise each time, and the calculate what works best for you.

If MH/J is important to you then let us know how efficient you manage to make your rig.  Mine is at 2.41 Mh/J.  My PSU is 89% efficient at my load, I'm running off of a HDD, and I'm running two Sapphire HD5850 Xtreme cards.

[film2240]

Wow!  I'm impressed with the large savings you are making by tweaking your BIOS.  switching off firewire for 5W, man!  When I switched off firewire the only detectable difference was that the firewire port wasn't lit up, the power drain didn't change at all for me.

In this case I stand corrected and do absolutely set about tweaking your BIOS as much as you can.  But even so, the efficiency of the PSU could save/cost you 50W so is worth considering at least.

I'm afraid I can't advise on PSUs.  I only have one miner and I bought my PSU with noise as the primary consideration.  For me the PSU is critical in building a mining rig (along with the cards and motherboard).  The chip, drives, RAM, OS, et cetera are good to get right but of secondary importance.  I personally never skimp on the power supply but for maximum profit you may want to go with something cheapish which can manage 86%+ at your mining load.  A typical positive attribute and one many people pay a lot for is for the PSU to be at least x% efficient at any load - give that you really don't need this shop around and look at the efficiency vs. load graphs for cheap PSUs.

As for voltages on the cards it really depends what you want out of your system.

• To maximise MH/J you will probably want to drop the voltage quite a bit (0.1V or more) and a little more still if you have many cards in one rig.
• To maximise profit then you may want to overvolt your cards by a small amount (0.05V is my guess) but this is assuming you have cooling sorted.
• To maximise MH/s then I find 1.25V is best (higher voltages hurt my stability due to the increased heat).

Of course, there are many factors: The cost of power; The market value of bitcoins; Your cooling; Your noise tolerance; How good at overclocking your particular cards are; even the OS!  I would get a PSU which is efficient at the power you expect to draw and for +/- 30%, use a power meter to measure power consumption at the wall, find your maximum stable clocks for a range of different card voltages and note power consumption/temperature/noise each time, and the calculate what works best for you.

If MH/J is important to you then let us know how efficient you manage to make your rig.  Mine is at 2.41 Mh/J.  My PSU is 89% efficient at my load, I'm running off of a HDD, and I'm running two Sapphire HD5850 Xtreme cards.

Actually most of my tweaks are done within windows,only the disabling of unneeded chipsets can be done at BIOS level such as the disabling firewire and other things.
As I have an Asus mobo,I can use a utility called EPU-6 which lets you tweak CPU clocks (as RAM clocks auto change with CPU clocks),changing fan speeds (full blast to silent mode),under volting and underclocking teh chipset itself,manage HDD times before shutting off,overclocking is enabled at turbo so you can overclock and underclock quite well with this utility.

It's best to enable 'green ethernet' with your device manager in windows (that saved me quite a bit) as it only switches on when network activity is there,it can also vary the power used based on network activity,think of it as the speedstep for the NICs.Power varies based on network activity and how long your cable is.Normally a NIC is running at full power regardless of what its doing so you're wasting power when it's doing nothing.

Is Silverstone a reputable PSU make like enermax? As I have to make sure that the PSU I buy doesn't fry my system like the 1 on my first comp did in early 2007 (That comp lived from 2004 til early 2007)

Thanx tho guys for the tips so far.

[deslok]

Yes they are tech review sites often comment on their various models high quality.
*edit*
Review of a silverstone psu
 http://www.anandtech.com/show/2561