|"The recent upgrade was the 6850 and the PSU "|
Did you install both of them at the same time ?
If you installed the HD 6850 first, the 300 watt power supply was indequate and the PS may have been damaged. Sometimes when a power supply is malfunctioning it damages something else on the computer.
AMD Radeon™ HD 6850 Graphics
- 500 Watt or greater power supply recommended
"Previously I used the onboard motherboard graphics (Radeon 4250) and a no-brand 300W power supply. This worked fine until just before the upgrade, whereby first I noticed graphics artefacts in every game: odd polygons sticking out of the ground and people’s faces. Weird. Around this time the computer also started completely freezing: but this only happened in windows, and not in safe mode. I’ll be honest and say the computer was a bit prone to overheating and switching itself off after a few hours of Mass Effect 2 at this point"
High end games tend to stress the CPU and the video adapter to the max - they both draw more current, and produce more heat.
The main chip that has the onboard video integrated into it has a large heatsink on it. That chip should never get too hot unless you had a seroius overheating problem inside the case.
- the CPU fan didn't come with the CPU and was inadequate
- the 300 watt power supply's fan was spinning slower than it should have been, or was not spiining at all. That's more likely to happen with an el-cheapo power supply that has only a 1 year warranty or less, which may have a fan with two cheap sleeve bearings, or one sleeve bearing, one ball bearing.
Your video symptoms also could have been caused by the 300 watt power supply being faulty, and it not responding to an increased load properly.
Sometimes when a power supply is malfunctioning it damages something else on the computer.
El-cheapo power supplies are a lot more likely to cause you problems.
What is the make and model of the 300 watt power supply ?
Or does you saying "no brand" indicate it's such an el-cheapo model that it doesn't have an identifiable brand ?
"No video output, not even during the boot process, cannot be a "windows thing", it's definitely faulty hardware."
..... or a problem with the hardware such as ram that is not properly seated, incompatible ram, etc. .
Usually that's the case.
However, in this case this mboard has a main chipset that supports Hybrid CrossfireX video - both the onboard video and the video on the video card in the PCI-E X16 slot working at the same time. .
In that case if the video chipset on the card in the slot is NOT supported by the Hybrid video feature, you MAY get no video from the video card and the
onboard video is still working with default bios settings, and in that case you must
change at least one setting from it's default setting in the mboard's bios Setup to get video from the card in the mboard slot.
In this case, the Hybrid CrossfireX video featutre probably ONLY works when the card in the PCI-E X 16 slot has a HD 3450 or a HD 3470 video chipset.
What applies to the 790GX, 780G, 780V, and 760G main chipsets probably applies to the main chipset on this mboard.
"I’ve tried lots of things since. Taking the graphics card and seeing if it outputs on the onboard."
If you HAVE changed settings in the bios so that the onboard video is actually disabled, or is NOT the first thing the bios tries to initialize first, then you won't get any video from the onboard video when you remove the HD 6850 card until the Cmos battery has been removed then re-installed, or until the Cmos has been cleared by moving a jumper on the mboared to the clear position, moving it back to the "normal" position.
In either case, you'll get a Cmos Checksum error or similar message the next time you boot the computer - you must go into the bios ansd set at least the current date and time, Save bios settings, to get rid of that message while booting the computer.
"People say I should hear a beep – is this only if a motherboard speaker is connected? I have one, but I’ve tried lots of times to work out where it plugs in – I came to the eventual conclusion that my motherboard doesn’t have that facility. Is that ridiculous? Here’s a diagram of the motherboard from the manual: "
If you heard a single beep, or sometimes it's a pair of beeps, while booting your computer when it worked fine previously, then the mboard or the case has something that is producing that sound.
That diagram is useless regarding determining whether that's on the mboard surface and is built in.
I Clicked on the picture of the mboard here.....
.....then savied it to my hard drive, opened it, and zoomed in on it - it appears there's no normal sized piezo sound device, and no flat on the the mboard cmos battery socket . (It may have a vertical socket for the Cmos battery, or a tiny rechargable battery.)
I looked at the manual for your mboard.
If there are pins you have to connect a case speaker or a piezo sound device to, they're shown in the manual somewhere.
The most common place to find those pins is on the front panel header for the power switch, reset switch, power and hard drive activity leds, etc. .
No pins for a speaker on System panel F_PANEL header
No mention of pins for speaker in manual
Searching for beep in the manual reveals there is a warning beep possible because the CPU fan header or Chassis fan header has a fan connected to it that is spinning slower than the minimum rpm setting in the bios, or it isn't spinning at all,
So - the mboard DOES have a sound producing device of some sort, somewhere - it must be very tiny.
If none of the above helps.....
Your Corsair power supply is probably much better quality than the 300 watt power supply, but any power supply can malfunction or fail completely - it's just a lot more likely with an el-cheapo PS.
Failing power supplies are common and can cause your symptoms.
Check your PS.
They often partially work, fans and hard drives may spin, leds may come on, yet you may get no video and the mboard will not boot all the way.
See response 4 in this:
The only way to rule out the power supply as the cause of your problem FOR SURE without buying a new one is to try your power supply with another working computer, or try a power supply from a working computer with your computer, if you can.
A power supply from another working computer should have a least a 500 watt capacity when the HD 6850 card is installed, or 300 nwatts when it's not installed.
Or - try the original 300 watt PS with your system when the HD 6850 card is not installed.
Other causes ?
Make sure that you DO NOT have a metal mounting post under the mboard in a place where there is no mounting hole for screw in the mboard - in that case the mis-placed metal mounting post may be intermittantly shorting something on the underside of the mboard.
Have you CHANGED which ram you have installed ? People often do that when they can't figure out why there system is not working properly.
If yes, not all ram that you might think should work fine is 100% compatible with your system.
In the worst cases of incompatibility your mboard WILL NOT BOOT all the way with it installed, and the mboard may not even beep - the ram has to be compatible with the mboard's main chipset, or in the case of recent mboards, compatible with the memory controller built into the cpu.
If you still have the ram that was installed when the system worked fine, and you know which module(s) it (they) is (are), try installing just that ram.
It is extremely RARE for ram that worked fine previously when installed in the SAME mboard to go "BAD".
It is easy to test for incompatible ram, or damaged ram, that has caused your mboard to fail to boot.
Make sure you have a speaker or speakers or the equivalent connected to the mboard so you can hear mboard beeps (see your mboard manual if you need to).
Remove the AC power to the case/power supply.
Remove all the ram.
Restore AC power.
Try to boot.
If nothing else is wrong, you will get no video but you will hear a pattern of beeps that indicate no ram is installed, or a ram problem.
E.g. for an Award bios or a bios based on one, that's often a beep of about a half second, silence for a half second, a beep of about a half second, silence for a half second, continuously.
Has there been a power failure event that happened since the last time the computer worked fine ? One caused by a lightning strike is the most likely to damage something on your computer. often the power supply if not more than that.
Have you been REMOVING the AC power to the casse / power supply AT ALL TIMES when you've been fiddling around with components or connections inside the case.
If you didn't do that AT ALL TIMES, you may have damaged something
"•Corsair 600W CX"
Builder series CX600 V2
•80 PLUS certified to deliver at least 80% efficiency at normal load conditions (20% to
•Dedicated single +12V rail offers maximum compatibility with the latest components
•Three year warranty
The manual for it shows it has two PCI-E connectors coming from the PS for video cards, but it doesn't say whether they're six "pin" or 8 "pin" (6 + 2 - the 2 "pin" part of it is detechable from the 6 pin par of it).
The Asus EAH6850 series apparently has two 6 "pin" power sockets.
Are you plugging in one connector from the power supply into each socket ?
If you're using a Y cable (one PCI-E connector to two PCI-E connectors) wiring adapter adapter with one PCI-E connector from the PS to connect to the two sockets on the card, that won't be able to supply enough current (amperage) to the card.
PSU Myths BUSTED
Myth 1: Only Single Rail Power Supplies Can Power Up High-end Graphics Cards!
Myth 2: A Single-Rail Power Supply Is More Powerful Than A Multi Rail Power Supply!
Myth 3: A Single Rail Power Supply Is As Safe As Multi Rail Power Supply!