My PC wont post then after resetting cmos its running again ,until a reboot.

[Ravens Nest]

I am stumped as my PC is acting strangely.

It works fine all day and sometimes for a few days, but then i will turn it off and when i come back to it will not POST (no beeps).

Pressing the power button sometimes the power light flashes on then turns off instantly, then you press again and it all powers up all fans running but does not POST (no beeping noises) and a blank screen.

I then have to turn it off at the mains, open the case and remove the CMOS battery for 30 seconds then replace it turn the power on it then boots i then alter the bios settings as they have all reset and its good again for maybe a couple of days then it starts all over again.

I have checked the HDD's they report no problems via SMART, would a HDD or memory problem cause it to not boot?

Is it worth running Memtest on my ram?

Also is the PSU getting flaky i wonder? its just when the power is off i press the power button and it shuts down straight away then i press again and its o.k. (This doesn't always happen, only when it will not POST)

These are my specs :-

Windows 7 premium
Asus P6T Deluxe V2
Intel Core i7 920 @ 2.67GHz Bloomfield 45nm Technology
6.00GB Triple-Channel DDR3 @ 534MHz (8-8-8-20)
AMD VTX3D HD7850 2GB
2TB Seagate ST2000DM001-1E6164 ATA Device (SATA) 31 °C
300GB Maxtor 6V300F0 ATA Device (SATA) 41 °C
OCZ StealthXStream 600W / Power Supply Unit / PSU / 120mm Fan

Voltages are :-
Hardware monitor Winbond W83667HG
Voltage 0 1.05 Volts [0x83] (CPU VCORE)
Voltage 1 1.77 Volts [0xDD] (VIN1)
Voltage 2 3.33 Volts [0xD0] (+3.3V)
Voltage 3 4.94 Volts [0xCE] (+5V)
Voltage 4 11.71 Volts [0xD2] (+12V)
Voltage 6 1.67 Volts [0xD1] (VIN6)
Temperature 0 67°C (152°F) [0x43] (SYSTIN)
Temperature 1 50°C (121°F) [0x63] (CPUTIN)
Temperature 2 2°C (34°F) [0x3] (AUXTIN)
Fan 1 2280 RPM [0x25] (CPUFANIN0)
Fan 2 1318 RPM [0x8] (AUXFANIN0)
Fan 3 2033 RPM [0x53] (AUXFANIN1)

Quad core temperatures are between 40-60°C

Any ideas suggestions are welcome

[Ravens Nest]

No reply's that's surprised me always found the folks at Hexus to be the most helpful, but no reply's yet.

I'm bumping the thread, Just hopeing someone might have some ideas..

[Rob_B]

Only thing I can suggest is the usual, try running with some hardware removed, it'll take a while but it'll narrow it down, also perhaps a dodgy cmos battery?

[Ravens Nest]

I have swapped the CMOS battery out, hasn't made any difference but thanks for the idea.
I have tried installing windows 7 on my other HDD but its still happened, i'd love to have a spare PSU to test it with but i dont know anyway who has one spare.
Wondering if anyone thinks my temps and voltage seem ok as well, from the information i got from HWmonitor.

[aramil]

Download and install memtest to a USB stick and boot to it and run some long passes on your RAM. See if it errors.

Try to reduce the load on the PSU by disconnecting all none OS drives/extra fans etc. and testing.

Hwmonitor looks like it is misreading values unless your CPU is at 150°c & your 12v line is @411v lol. It would do that on my old Asus p5kc too.

[Ravens Nest]

Thanks i will try memtest on long passes for the ram to hopefully take that out of the equation.
It says the CPU is 50°c 152°F and the 12V line is 11.71V, the wording is a bit near to the Voltage 4 and Temperature 1 so may look like 150 and 411

[stilkun]

Have you removed the graphics card and remove other hardware leaving only essential components running?

It could be either the motherboard, CPU or PSU affecting it as from what I understand that the CPU will load/process POST from BIOS before booting into the system.

[Ravens Nest]

Its a bit tricky as it does it every now and then and a CMOS reset gets it going again, but i have tried taking all components out and another graphics card it will still not POST.

But take the CMOS battery out and 30 secs later putting it back in it boots up fine.
I will try unplugging my DVD drive and leaving only 2GB ram in one slot to see it if runs ok, hard to narrow it down as it will work fine for 2-3 days then decide not to POST again.

[MrJim]

My first thought was the PSU - I've not had much luck with OCZs in the past, it's possible that it's a bit flaky. If you don't have the option of borrowing a different one, diagnosing the problem could be tricky though.

Does your motherboard have a power-on button on the board itself? It's a long shot, but it's possible that the power-switch on your case is a bit flaky too. Cheap cases often have cheap switches in my experience!

[kalniel]

I then have to turn it off at the mains, open the case and remove the CMOS battery for 30 seconds then replace it turn the power on it then boots i then alter the bios settings as they have all reset and its good again for maybe a couple of days then it starts all over again.

That's where I'd start looking. Seems like it's not quite stable at your chosen settings - could be that the hardware has deteriorated slightly, or you've got software changes that are more sensitive to your supplied frequencies/timings/voltages.

The first thing I'd change is the memory timing - drop to CAS9 based timings, and 2T command rate.

[Zak33]

Don't suppose you've got lots of USB stuff plugged in? USB hard drived, pen drives etc. If you have take them all out except the mouse and keyboard.

I've had 2 flaky USB pen drives that prevented stable boots.

if that's not it then: did you built the PC yourself.. ?

I'd take the heatsink off the CPU and reapply thermal paste

Sometimes CPU's just mess you about unless they're happy.

Lastly Id also look in the case for a loose wire shorting the motherboard out.

Any wires... power leads,... loose fan cable ens unplugged... even a metal washer sliding around.....

[Ravens Nest]

My first thought was the PSU - I've not had much luck with OCZs in the past, it's possible that it's a bit flaky. If you don't have the option of borrowing a different one, diagnosing the problem could be tricky though.

Does your motherboard have a power-on button on the board itself? It's a long shot, but it's possible that the power-switch on your case is a bit flaky too. Cheap cases often have cheap switches in my experience!

You've had problems with OCZ, i know if i move the powerlead at all it makes a electric buzzing noise, but its been like that for years. The case is a coolermaster CAC-T01 i must admit i have thought the power button may have become faulty creating a short.

That's where I'd start looking. Seems like it's not quite stable at your chosen settings - could be that the hardware has deteriorated slightly, or you've got software changes that are more sensitive to your supplied frequencies/timings/voltages.

The first thing I'd change is the memory timing - drop to CAS9 based timings, and 2T command rate.

I will give CAS9 2T a try

Don't suppose you've got lots of USB stuff plugged in? USB hard drived, pen drives etc. If you have take them all out except the mouse and keyboard.

I've had 2 flaky USB pen drives that prevented stable boots.

if that's not it then: did you built the PC yourself.. ?

I'd take the heatsink off the CPU and reapply thermal paste

Sometimes CPU's just mess you about unless they're happy.

Lastly Id also look in the case for a loose wire shorting the motherboard out.

Any wires... power leads,... loose fan cable ens unplugged... even a metal washer sliding around.....

I only have my keyboard mouse and my PS3 eye as a Skype camera plugged in via USB, but it has been fine for ages.
I stripped the case down and rebuilt it, the only loose cable i have is an earth cable near the front of the case loose. thats been like that since i built it but actually where can i screw that in as it would be better earthed lol

I will take it apart again and change some screws over and put more fibre washers on the motherboard, its all worth a try.

Does everyone think my Temperatures are within safe limits i benchmarked Thief 4 times and my CPU temperatures are between 40°C - 62°C.
I have changed the thermal compound about 6 months ago but wont hurt reapplying it, whats the best way you have found to apply it?

[stilkun]

Does everyone think my Temperatures are within safe limits i benchmarked Thief 4 times and my CPU temperatures are between 40°C - 62°C.
I have changed the thermal compound about 6 months ago but wont hurt reapplying it, whats the best way you have found to apply it?

Sounds about right, the temp looks good for CPU. Using stock fan on your cpu? My method is carefully spread the paste across the cpu area I have applied before I putting on the heatsink.

[kalniel]

In contrast I'm a fan of the grain of rice sized amount in the middle and letting the heatsink spread it.

[malfunction]

What's the vcore set to in the BIOS? 1.05V seems low but it could be being reported incorrectly. Presumably 1.05V is the idle / 6x multi voltage and it goes up under load? Also have you tried stress testing the machine while it's booting and running OK? Might be unstable with your BIOS settings or might be a stick of RAM on the way out (it happens though not often). Also:

What BIOS settings are you changing? Are you running at stock or overclocking?

[Ravens Nest]

What's the vcore set to in the BIOS? 1.05V seems low but it could be being reported incorrectly. Presumably 1.05V is the idle / 6x multi voltage and it goes up under load? Also have you tried stress testing the machine while it's booting and running OK? Might be unstable with your BIOS settings or might be a stick of RAM on the way out (it happens though not often). Also:

What BIOS settings are you changing? Are you running at stock or overclocking?

I have the BIOS settings at default no over or underclocking at all, i checked the BIOS and VCORE is at Auto and should be minimum 1.1V.

It is between 1.048V and 1.256V maximum seems erratic to me CPU Powers and Current are all over the place between 6W and 20W! so i think the PSU is on its way out.

Anyone got a good replacement PSU for my specs?

Not stress tested it on boot, how do you do that? but i have run games at full settings with all fans blazing and its been great until you turn the PC off..

I only change the settings for things i dont need like Splash screen, Firewire, Sound card i leave everything else.