Small Power Usage Test

[Interstellar]

Thought this might interest people who like to save power.

 

Setup:

 

AMD Phenom II X2 550 BE unlocked to 4 cores, 3.2Ghz, 1.3V.

Asus M4A78LT-M - everything in BIOS not used, turned off.

4x2GB PC3-8500 1066Mhz @ 1333Mhz, 7-7-7-21, 1.5V.

PSU: BeQuiet Pure Power L7 530W Power Supply, Plus rated. ~80% efficiency.

 

In S3 sleep: 2-3W

 

Idle

Not unlocked (2 active cores), 925mv @ 800MH, 1333Mhz memory = 44.5-45.5W

Unlocked (4 active cores), 950mv @ 800MHz, 1333Mhz memory = 44.5-45.5W

Unlocked (4 active cores), 900mv @ 800MHz, 1333Mhz memory = 43.5-44.5W (~ -1W)

Unlocked (4 active cores), 900mv @ 800MHz, 1066Mhz memory = 43.5-44.5W (No change)

 

Unlocked (4 active cores), 1300mv @ 3200MHz, 1333Mhz memory = 74.5-75.5W (+20W from 900mv!)

 

 

Load

Not unlocked (2 active cores), 1300mv @ 3200MHz, 1333Mhz memory = 116-118W (+ 72W from idle)

Unlocked (4 active cores), 1300mv @ 3200MHz, 1333Mhz memory = 164-166W (+48W from 2 cores only)

Unlocked (4 active cores), 1300mv @ 3200MHz, 1066Mhz memory = 162-163W (~ -2W from 1333Mhz memory).

 

Disks add 4.5-5.5W if it's a green drive and 5.5-6.5W if it's a 7200RPM drive.

 

 

So for 95% of the time when the server is doing nothing the dual to quad unlock changes nothing.

Benefits the transcode ability of PS3MS server and the IO when multiple things are happening.

 

Interesting results IMO. Especially saving 1W just by dropping the idle voltage down to 900mv from 950mv!

 

[Rajahal]

That is surprising, thanks for sharing!  By 'Load' do you mean a load on the CPU (such as transcoding media) or a load on the disks (such as transferring files)?  Also keep in mind that unlocking a CPU adds an element of instability to your server that may come back to bite you later.  If you've run your own tests and are satisfied that your unlocked CPU is stable, then great.  However, this isn't something that I would recommend to everyone.

[Interstellar]

That is surprising, thanks for sharing!  By 'Load' do you mean a load on the CPU (such as transcoding media) or a load on the disks (such as transferring files)?  Also keep in mind that unlocking a CPU adds an element of instability to your server that may come back to bite you later.  If you've run your own tests and are satisfied that your unlocked CPU is stable, then great.  However, this isn't something that I would recommend to everyone.

 

Load is Prime95 on 2/4 threads using 1.8GB of ram (so four instances of prime95 as a single instance can only use ~3GB).

 

So essentially the hardware power usage (minus HDs) ranges from ~44W to 166W depending on it's P-state and load.

 

There is no change from dual to quad because the disabled cores (even if they are 100% working - simply because they need more cheaper CPUs) are still powered, and hence there is no change from dual to quad.

 

Another test:

Unlocked (4 active cores), 1300mv @ 3200MHz, 1333Mhz memory = 74.5-75.5W (+20W from 900mv!)

 

 

As for stability:

 

Tested for 72 hours at 3.4Ghz in dual core mode with 1.3V and 1066MHz memory.

Tested for 48 hours at 3.2Ghz in quad core mode with 1.3V and 1333MHz memory.

 

 

[dgaschk]

Unlocked cores are likely to fail on some instruction. There was an example of an unlocked CPU running unRAID perfectly but when Java was loaded on the server the CPU crashed. The server was fine without Java.

[Interstellar]

Unlocked cores are likely to fail on some instruction. There was an example of an unlocked CPU running unRAID perfectly but when Java was loaded on the server the CPU crashed. The server was fine without Java.

 

Well things like this are harder to test for.

 

However Prime95 and Linux should pickup anything un-toward with the critical parts of the CPU for storage reliability!

[dgaschk]

This is true; however, a single core is fine for basic file serving. Unlocking a core to do video transcoding may cause an unexpected crash sometime down the road. Just expect random crashes.

 

Cores are not locked for marketing purposes. The cores are locked because they failed testing. This allows a cheaper manufacturing process. Some percentage of cores fail testing and are locked. The chips where both cores pass testing cost more for a reason.

 

It's true that an unlocked core may run without crashing. But the proper combination of instructions will cause a crash.

[Interstellar]

This is true; however, a single core is fine for basic file serving. Unlocking a core to do video transcoding may cause an unexpected crash sometime down the road. Just expect random crashes.

 

Cores are not locked for marketing purposes. The cores are locked because they failed testing. This allows a cheaper manufacturing process. Some percentage of cores fail testing and are locked. The chips where both cores pass testing cost more for a reason.

 

It's true that an unlocked core may run without crashing. But the proper combination of instructions will cause a crash.

 

I'm afraid that is not entirely true for every single chip out there.

 

Quads (Deneb) and 6-core (Thurban) chips are sold locked, even if they are 100% working chips.

 

If AMD sells more 3.2GHz duals than it does quads (Say 75% of a 10k unit batch) and they have a yield of 50% 3.2GHz quad core chips, 25% of those 100% working quads get sold as dual cores to satisfy demand. As the process improves they launch higher clocked chips and/or reduce the price of each unit.

 

Most recently seen by the W3680 ($999 before) dropping to ($650 1000 unit price). It's still the second fastest 6 core Intel make and it hasn't been replaced yet by SB-E.

 

It is true however that there is no gaurantee buying a dual for it to operate 100% as a quad, but there are chips (seemingly like mine) that are simply 100% good dies  sold as a dual.

 

However two months on from unlocking my dual and doing a number of parity checks and streaming a number of 1080p films with no issues I think i've found a winner!