Too small PSU? 400W for phenom ii x4 955 + hd radeon 7850 overclocked

[Hvardl]

Hi!
I have a pc with following specs:
4x2gb ddr3 1333mhz ram
ASUS M4A785TD-V EVO
AMD Phenom II X4 955 Black Edition (OC: 4.0ghz 1.55volt)
HD Radeon 7850 (GPU clock: 1200, mem clock 1400 and VDDC 1.225)
Silver Power SP-SS400 400W PSU

At max (cpu and gpu stress test) the pc draws 400w from the net (energylogger, see picture).
When I try to up clock the cpu more, the pc gives me a black screen then restarts without turning off. Could my PSU stop me from overclocking my cpu and gpu further? Would you say that the PSU is too weak for the job?

 

[jackal575]

It sounds like it, yes.

Check this site, it also has a section for you to calculate the overclocked CPU power usage in W and use it to calculate total load of the system

http://www.extreme.outervision.com/psucalculatorlite.jsp

 

[bignastyid]

Yes you need a bigger PSU. It's a good thing that 400w unit is a good quality unit(made by seasonic) a lower quality 400w PSU would have burnt out and possibly damaged other components. I would suggest atleast a good quality 500w unit for what you are trying to do.

 

[nostall]

Minimum power recommended for a system with one 7850 is 500 watts with at lease 21amps of current on the +12v rail.
Since you are overclocking you will need more power then this recommendation. The important specification is not total wattage, but the amount of current (amperage) that can
be delivered on the +12V rail(s) continuously at an operating range of 40-50C.
A good 500watt unit would be a minimum starting point, but if it were me I would opt for something around 600 watts.
Silver Power has a good reputation, but if you start shopping you will want something from Tier 1,2a,or 2b from this list:
http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html

 

[Quixit]

I normally err on the side of caution and try not to load my PSUs over 80% (DC side, not at the wall of course). I don't know how efficient your power supply is so if it was theoretically 80% efficient and is drawing 403Watts at full load I'd consider that on the line for me.

As for why your overclock is failing, you might just be at the top of the potential of your particular Phenom chip, if I recall correctly the higher-end Phenoms never overclocked particularly well.

In conclusion, it's a good idea to buy a more powerful power supply but I'm not sure you're going to see a huge overclock out of it. You never mentioned what CPU cooler you're using so if you're using the stock one, replace it with something decent. AMD's stock coolers are not designed for overclocking at all.

 

[Hvardl]

Thanks for the fast replies everyone!
I just bought myself a slightly used XFX Pro 850W XXX Edition. Should do the job right? It's an overkill atm, I know, but I will be upgrading the computer at the end of this year for 4k gaming so I can use it then.
Quixit: I am using a CoolIT VANTAGE A.L.C. liquid cooler. I know it might not do any good changing the psu but sounds like bad things can happen if I don't 😛

 

[nostall]

Thanks for the fast replies everyone!
I just bought myself a slightly used XFX Pro 850W XXX Edition. Should do the job right? It's an overkill atm, I know, but I will be upgrading the computer at the end of this year for 4k gaming so I can use it then.
Quixit: I am using a CoolIT VANTAGE A.L.C. liquid cooler. I know it might not do any good changing the psu but sounds like bad things can happen if I don't 😛

Better to have too much then not enough. Let us know if it solves the problem.

 

[Hvardl]

I will run and get it in an hour, will let you know after that!

 

[Hvardl]

With the new psu I could clock it a little higher, not much tho. The pc is more stable atm. Feeling confident it was a good investment. Thanks for all the great answers everyone, really helped!
Btw; I know have the highest 3dmark Fire strike score for the 955/ hd 7850 combo 😉

 

[nostall]

With the new psu I could clock it a little higher, not much tho. The pc is more stable atm. Feeling confident it was a good investment. Thanks for all the great answers everyone, really helped!
Btw; I know have the highest 3dmark Fire strike score for the 955/ hd 7850 combo 😉

Great! Hope it stays stable.

 

[Chester Rico]

If it was a *good* 400W PSU it might even work. But I'd get a 500W one for that setup. Make sure you buy a quality one, not some no-name crap. PSU quality is important.