I recently bought a new ASUS EAH5850 graphics board. I installed it a custom PC which had an ASUS p5n-e SLI mobo along with a 500w Thermaltake W0093RU power supply.

Sometimes when doing a cold boot the 5850's fan will run at full speed and the PC will not boot. Powering off by holding down the power button and powering back on sometimes remedies the situation and everything boots normally. Warm reboots also never seem to have problems. For some reason though cold boots almost always do. Another issue I notice is that when the PC does boot normally it takes longer (+30 secs) to POST than with my last video card. I flashed the mobo with the latest available BIOS but it had no effect.

Is my problem a power issue or incompatible motherboard or something else I'm missing?

  • So I'm assuming from your comments, it will boot fine without the card installed? If so, obviously the card is at fault, it is strange though that you are reporting different results with different boots. Checked BIOS settings for video configurations? Perhaps, disabling quick boot see if it changes anything on a cold boot? – AdminAlive Oct 23 '09 at 16:35
  • I was thinking of power issues because the card requires 2 12v power PCI power connectors on it. My power supply had 1 already and the card came with an adapter that goes from 2 molex to 1 PCI for the other. BIOS settings look OK and I don't think I have quick boot enabled but it's possible...I'll have to check. – Kris Oct 23 '09 at 18:58
  • I recently built a new PC and used this card in it and it is working fine. The new PC was built with a 750W PSU and I never had any video card issues so I'm pretty confident my original problem was power related. – Kris May 14 '10 at 17:25
  • This cold boot problem seems to happen with a lot of 5800 series cards, and some manufacturers have even released updated video card BIOSes to remedy the problem. – Andrew Mao Dec 30 '14 at 21:12

It could easily be power related.

I can't find any specs for your ASUS card, but the AnandTech's review shows that the Radeon HD 5850 card is rated at about 151W which could be up to 12.58A off of the 12V power rail. Keeping in mind that high power cards need to charge up their capacitors when power is first applied, you could be in for a problem especially if you have more devices on your 12V power rail.

Your power supply has two 12V power rails. 12V1 has a max load of 14A and 12V2 has a max load of 15A. 12V1 supplies the main 24-pin power connector and the SATA power connectors. 12V2 supplies the PCIe power connector. Unfortunately, the users manual doesn't specify which rail the 12V comes from with the peripheral power connector and 2x2 power connector. If it is 12V1, you could be overloading the 12V1 power rail. The only way to know for sure is to measure the current draw, which is hard to do without a current probe or a current meter. An alternative is to try another power supply with two PCIe power connectors and more than two 12V power rails or 12V power rails with > 15A max current.

As far as the 30s to POST, it would be really nice if you had a POST card to figure out what POST code is displayed when it it pausing. This could be caused by the card having trouble powering up.


  • The control of the 12V power supply is by the power button on the motherboard. The 12V power stays up during a warm reboot and doesn't transition states.
  • The fan coming on full blast is a safe default until the fan control is enabled by the card's video BIOS.
  • BTW, it's really not 2 12V rails...it is one rail with 2 current limiters. Actual dual rail PSUs are extremely rare. Another good alternative is a SINGLE rail power supply. Basically, it eliminates these "current limiter" issues entirely. – Stephen Jan 21 '10 at 8:41
  • The User Manual states in the Technology Features that it has "Dual +12 V Rails." That could be inaccurate, though. I don't have any intimate knowledge of the design of this specific power supply. – hanleyp Jan 23 '10 at 23:45

mine as well had the same problem.. powercolor hd 5850 100% fan speed on cold boot and system doesn't start up. fixed it by updating the bios of my mobo.

here's my rig: asus M4A785td-V evo HD 5850 HEC cougar 700w


I had this exact same problem this weekend. For me it was the power from my 1000w Powersupply. The 5850 has qty2 6pin connectors, in the instructions it said I could use either 1 or 2 connectors. I only used 1 and figured I'd save a cable, well bad mistake because the card wouldn't post and I spent an hour trying to figure out why. I added the second power connector and it fired up right away. Hope this helps someone


I just wanted to add to this for prosperity.

I just experienced this tonight, 3 days after I installed my 5850 on my gibabyte GA-770T-USB3 motherboard the exact same thing happened to me. Black screen, gpu fan maxed out, cpu fan running, no post beep.

Really freaked me out.

Turned out that the 10 pin power connector on my motherboard was loose.


I've verified my issue has nothing to do with the graphics card. I think it's the mobo. I dont know if this is the correct way to link in forums but you can see full details here:

Power cycles on/off 3 times before booting properly from cold start, no other issues (New System)


So i got a not at all helpful response from Gigabyte...

Dear Sir,

Thank you for your kindly mail and inquiry. About the issue you mentioned, we suggest you to test this VGA card on other computer and see how it works. Or if possible, please kindly test other VGA card on your motherboard and try again later. Unfortunately, if the problem still remains, a further testing or examination to your system might be required. We are really sorry for the inconvenience you have with our product.

Warranty and RMA issues are normally arranged by your supplier. The warranty terms are dependent on your sale of contract and are what ever your supplier sold you. Please kindly contact your supplier and they shall follow a standard RMA procedure and send the product to the local distributor for RMA service for you. We are sorry if there is any inconvenience.

If your supplier cannot help you, please contact with local distributor for further assistance. For their information, please kindly visit our website by following link: CLICK HERE.

At last, if you still have any further question to this issue or suggestion about our products/service, please do not hesitate to contact with us. If you have any issue different from original, make sure you issue a new form in order to get proper assistance and it may be response faster as well. We will try our best to help you resolve the problem ASAP.

Best Regards,


that's all... :(


With many cards, the fan will run at full speed until the driver loads. If some problem prevents the driver from loading, e.g. the system does not boot successfully, the fan will continue to run at full speed. I suspect the fan running at full speed is a symptom of another boot problem.

Since it only happens with cold boots, could be related to hard drives and/or optical drives spinning up during power-on. You might look into staggering the drive startup (google it) or test with fewer drives to see if that's the problem.

protected by studiohack Feb 18 '11 at 14:05

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