Updated from 12:08 9.m. EST

The PC sales slump continues to crush

Intel's

(INTC) - Get Report

fourth-quarter numbers.

The Santa Clara chip giant warned Wednesday that its early sales tally shows a top line of $8.2 billion, down 20% from the prior quarter and 23% below year-ago levels. Analysts had been looking for revenue of $8.7 billion.

This is Intel's

second downward revision

to its sales guidance in two months. In November, Intel cut its sales forecast to between $8.7 billion and $9.3 billion, down from between $10.1 billion and $10.9 billion previously. Then, as today, the company Wednesday blamed "further weakness in end demand and inventory reductions" by its PC customers for the even lower sales performance.

The company also said its gross margin will be "at the bottom" of its previous forecast of about 55%. Intel entered the quarter ending last month expecting gross margins to be around 59%. Investors tend to see the erosion in margin as a clear sign that Intel has had to cut prices as chip inventory piles up.

The news comes as PC makers like

Dell

(DELL) - Get Report

and

Hewlett-Packard

(HPQ) - Get Report

struggle to keep computer sales humming amid an invasion of cheaper netbooks from Asian outfits like Asus and Acer.

Intel also didn't fare well with its WiMax investment.

To date, Intel has provided at least $1.9 billion in financing to

Clearwire

(CLWR)

and a subsequent joint venture with

Sprint

(S) - Get Report

. On Wednesday, Intel said it plans to take a $950 million impairment charge to account for the drop in Clearwire's market value. Intel now says its expects the WiMax venture will amount to a net equity loss of between $1.1 billion and $1.2 billion. That loss estimate is far steeper than the $50 million Intel previously expected.

The company says it will deliver its full fourth-quarter earnings report on Jan. 15.

Intel shares closed Wednesday's trading session down 93 cents, or 6.1%, to $14.44.